Halacha

הלכה א
שִׁשָּׁה דְּבָרִים מוֹנְעִין נְשִׂיאַת כַּפַּיִם. הַלָּשׁוֹן. וְהַמּוּמִין. וִהָעֲבֵרָה. וְהַשָּׁנִים. וְהַיַּיִן. וְטֻמְאַת הַיָּדַיִם. הַלָּשׁוֹן כֵּיצַד. הָעִלְּגִים שֶׁאֵין מוֹצִיאִין אֶת הָאוֹתִיּוֹת כְּתִקּוּנָן כְּגוֹן שֶׁקּוֹרִין לַאֲלֵפִי״ן עַיְנִי״ן וּלְעַיְנִי״ן אֲלֵפִי״ן אוֹ לְשִׁבּלֶת סִבּלֶת וְכַיּוֹצֵא בָּהֶן אֵין נוֹשְׂאִין אֶת כַּפֵּיהֶן. וְכֵן כְּבֵדֵי פֶּה וּכְבֵדֵי לָשׁוֹן שֶׁאֵין דִּבְרֵיהֶם נִכָּרִים לַכּל אֵין נוֹשְׂאִין אֶת כַּפֵּיהֶן:
כסף משנה
1.
There are six factors that prevent [a priest] from reciting the priestly blessings: [an inability] to pronounce [the blessings properly],1as explained in this halachah physical deformities,2as explained in Halachah 2 transgressions,3as explained in Halachah 3 [lack of] maturity,4as explained in Halachah 4 intoxication,5as explained in Halachah 4 and the ritual impurity of [the priest's] hands.6as explained in Halachah 5
[An inability] to pronounce [the blessings properly]:7Note the discussion of this difficulty with regard to the choice of a chazan, Chapter 8, Halachah 12. What is implied? Those who cannot articulate the letters properly8e.g., those who read an aleph as an ayin and an ayin as an aleph - if the first word of the second priestly blessing, יאר is read with an ע instead of an א, the phrase את פניו אליך יאר ה' becomes a curse rather than a blessing. - e.g., those who read an aleph as an ayin and an ayin as an aleph, or who pronounce shibbolet as sibbolet9i.e., reading a shin as a sin. See Judges 12:6. and the like10e.g., who read a chet like a hay

should not recite the priestly blessings. - The later authorities explain that, if, as in many communities of the present day, the overwhelming majority of the people do not know how to differentiate between an ע and an א, a priest should not be disqualified because of this factor, since the meaning of the blessing is not changed (Magen Avraham 128:46). The Turei Zahav (128:90) states that even if a speech fault is common, but not overwhelmingly common - e.g., the substitution of a sin for a shin - a priest should not be disqualified, because such an error will not arouse the attention of the listeners. Nevertheless, this position is not accepted by all authorities.
- should not recite the priestly blessings.
Similarly, a stutterer or one who speaks unclearly, whose words cannot be understood by everyone,11included in the category are people with other speech defects - e.g., a person who lisps should not recite the priestly blessing.

הלכה ב
הַמּוּמִין כֵּיצַד. כֹּהֵן שֶׁיֵּשׁ מוּמִין בְּפָנָיו אוֹ בְּיָדָיו אוֹ בְּרַגְלָיו כְּגוֹן שֶׁהָיוּ אֶצְבְּעוֹתָיו עֲקֻמּוֹת אוֹ עֲקֻּשּׁוֹת אוֹ שֶׁהָיוּ יָדָיו בּוֹהֲקָנִיּוֹת לֹא יִשָּׂא אֶת כַּפָּיו לְפִי שֶׁהָעָם מִסְתַּכְּלִין בּוֹ. מִי שֶׁהָיָה רִירוֹ יוֹרֵד עַל זְקָנוֹ בְּשָׁעָה שֶׁהוּא מְדַבֵּר וְכֵן הַסּוּמָא בְּאַחַת מֵעֵינָיו לֹא יִשָּׂא אֶת כַּפָּיו. וְאִם הָיָה דַּשׁ בְּעִירוֹ וְהַכּל הָיוּ רְגִילִים בְּזֶה הַסּוּמָא בְּאַחַת מֵעֵינָיו אוֹ בְּזֶה שֶׁרִירוֹ זָב מֻתָּר לְפִי שֶׁאֵין מִסְתַּכְּלִין בּוֹ. וְכֵן מִי שֶׁהָיוּ יָדָיו צְבוּעוֹת אִסְטִיס וּפוּאָה לֹא יִשָּׂא אֶת כַּפָּיו. וְאִם רֹב אַנְשֵׁי הָעִיר מְלַאכְתָּן בְּכָךְ מֻתָּר לְפִי שֶׁאֵין מִסְתַּכְּלִין בּוֹ:
כסף משנה
2.
Physical deformities: What is implied? A priest should not recite the priestly blessings if he has blemishes on his face, hands, or feet1for all of these can be seen be the people while the priests recite the blessings. The Shulchan Aruch (Orach Chayim 128:30-31) states that in places where the priests cover their faces and hands with their tallitot and wear socks while reciting the blessings, even these blemishes do not disqualify a priest from reciting the blessings. - for example, his fingers are bent over, crooked, or covered with white spots2for they will attract the people's attention - and distract their concentration on the blessings.
A person whose spittle always dribbles when he speaks, and also a person who is blind in one eye should not recite the priestly blessings - for the same reasons as mentioned above. In places where the priests cover their faces, a priest with such a difficulty may also bless the people.
- for they will attract the people's attention.
A person whose spittle always dribbles when he speaks, and also a person who is blind in one eye should not recite the priestly blessings. However, if such a person was well known in his city and everyone was familiar3Generally, this refers to a person who lives within a city for at least thirty days (Shulchan Aruch, loc. cit. 128:30). with the person who was blind in one eye or whose spittle dribbled, he may recite the priestly blessing, for he will not attract their attention.4with the person who was blind in one eye or whose spittle dribbled, he may recite the priestly blessing, for he will not attract their attention.
Similarly,5i.e., for the same reasons a person whose hands were colored purple or scarlet should not recite the priestly blessings. If the majority of the city's population is involved in such a profession,6or if the people of the city are familiar with him (Shulchan Aruch, loc. cit., 128:32). he is permitted, for this does not attract the people's attention.

הלכה ג
הָעֲבֵרָה כֵּיצַד. כֹּהֵן שֶׁהָרַג אֶת הַנֶּפֶשׁ אַף עַל פִּי שֶׁעָשָׂה תְּשׁוּבָה לֹא יִשָּׂא אֶת כַּפָּיו שֶׁנֶּאֱמַר (ישעיה א טו) ״יְדֵיכֶם דָּמִים מָלֵאוּ״ וּכְתִיב (ישעיה א טו) ״וּבְפָרִשְׂכֶם כַּפֵּיכֶם״ וְגוֹ׳‎. וְכֹהֵן שֶׁעָבַד כּוֹכָבִים בֵּין בְּאֹנֶס בֵּין בִּשְׁגָגָה אַף עַל פִּי שֶׁעָשָׂה תְּשׁוּבָה אֵינוֹ נוֹשֵׂא אֶת כַּפָּיו לְעוֹלָם שֶׁנֶּאֱמַר (מלכים ב כג ט) ״אַךְ לֹא יַעֲלוּ כֹּהֲנֵי הַבָּמוֹת״ וְגוֹ׳‎. וּבְרָכָה כַּעֲבוֹדָה הִיא שֶׁנֶּאֱמַר (דברים י ח) ״לְשָׁרְתוֹ וּלְבָרֵךְ בִּשְׁמוֹ״. וְכֵן כֹּהֵן שֶׁהֵמִיר לְעַכּוּ״ם אַף עַל פִּי שֶׁחָזַר בּוֹ אֵינוֹ נוֹשֵׂא אֶת כַּפָּיו לְעוֹלָם. וּשְׁאָר הָעֲבֵרוֹת אֵין מוֹנְעִין:
כסף משנה
3.
Transgressions: What is implied? A priest who killed someone should never recite the priestly blessings, even if he repents,1The Ramah (Orach Chayim 128:35) allows a priest who repents after committing such a sin to bless the people, so that "the door will not be closed to those who repent." as [implied by Isaiah 1:15 which] states: "Your hands are full of blood,"2the killing of a colleague and states:3The order of these phrases in the Bible is the opposite of the order in which they are quoted by the Rambam.
"When you spread out your hands, I will hide My eyes from you." - Once a person has taken a life, God will not let him serve as a medium to convey blessing on the people.
A priest who served false gods, even if he was compelled to do so - See Hilchot Yesodei HaTorah 5:2-4, which states that a person should sacrifice his life rather than submit to pressure to worship false gods. Nevertheless, if he fails to make this sacrifice, he is not punished by an earthly court for his sin.
"When you spread out your hands, I will hide My eyes from you."
A priest who served false gods, even if he was compelled to do so or did so inadvertently4or without knowing that the worship of this god was forbidden - though he has repented5may never recite the priestly blessing, as [can be inferred from II Kings 23:9, which] states: "However, the priests of the high places shall not ascend [to God's altar in Jerusalem]." - This verse describes the efforts of King Josaiah to cleanse Judah from the pagan practices introduced by his father and grandfather. - may never recite the priestly blessing, as [can be inferred from II Kings 23:9, which] states: "However, the priests of the high places shall not ascend [to God's altar in Jerusalem]." [The recitation of the priestly] blessings is equated to service [in the Temple],6Note the Rambam's comments, Hilchot Bi'at HaMikdash 9:13:
Any priest who served false gods, whether willingly or inadvertently - even though he sincerely repents - should never serve in the Temple.... If he transgressed and offered a sacrifice, his sacrifice is not a "pleasing fragrance."
as [Deuteronomy 10:8] states: "to serve Him and to bless in His7Many of the later authorities maintain that this association is only a point of Rabbinic Law, and the mention of Biblical verses is only an asmachta (allusion). However, there is no indication of such a concept in the Rambam's words. name."
Similarly, a priest who converted8without actually serving the false gods to the worship of false gods9The Magen Avraham 128:54 states that even someone who converts to Islam - which does not involve idol worship - is not allowed to recite the priestly blessings. - even though he repents10In this instance, as well, the Ramah (loc. cit.:37) allows a priest to bless the people if he repents. - may never recite the priestly blessing. Other transgressions11The Mishnah Berurah 128:26 notes that a person who desecrates the sanctity of the Sabbath is considered as one who adopted paganism, and, therefore, should not be allowed to recite the priestly blessing.
Rav Moshe Feinstein (Iggerot Moshe, Orach Chayim I, 33) states that present circumstances differ from those during the Mishnah Berurah's era, and, at present, priests who violate the Sabbath laws are not judged as severely and may bless the people. Nevertheless, he agrees that if restricting such individuals from reciting the priestly blessings may motivate them to increase their Sabbath observance, they may be prevented from blessing the people.
do not prevent [a priest from blessing the people].12See Halachot 6 and 7.

הלכה ד
הַשָּׁנִים כֵּיצַד. כֹּהֵן נַעַר לֹא יִשָּׂא אֶת כַּפָּיו עַד שֶׁיִּתְמַלֵּא זְקָנוֹ. וְהַיַּיִן כֵּיצַד. מִי שֶׁשָּׁתָה רְבִיעִית יַיִן בְּבַת אַחַת אֵינוֹ נוֹשֵׂא אֶת כַּפָּיו עַד שֶׁיָּסִיר אֶת יֵינוֹ מֵעָלָיו לְפִי שֶׁהֻקְּשָׁה בְּרָכָה לַעֲבוֹדָה. שָׁתָה רְבִיעִית יַיִן בִּשְׁתֵּי פְּעָמִים אוֹ שֶׁנָּתַן לְתוֹכוֹ מְעַט מַיִם מֻתָּר. וְאִם שָׁתָה יוֹתֵר מֵרְבִיעִית אַף עַל פִּי שֶׁהָיָה מָזוּג אַף עַל פִּי שֶׁשְּׁתָאוֹ בְּכַמָּה פְּעָמִים לֹא יִשָּׂא אֶת כַּפָּיו עַד שֶׁיָּסִיר אֶת יֵינוֹ מֵעָלָיו. וְכַמָּה הִיא רְבִיעִית אֶצְבָּעִים עַל אֶצְבָּעִים בְּרוּם אֶצְבָּעִים וַחֲצִי אֶצְבַּע וְחֹמֶשׁ אֶצְבַּע כְּגוּדָל. וְזֶה הָאֶצְבַּע שֶׁמּוֹשְׁחִין בּוֹ בְּכָל הַתּוֹרָה כֻּלָּהּ הוּא הַגּוּדָל וְהוּא הַנִּקְרָא בֹּהֶן יָד:
כסף משנה
4.
[Lack of] maturity: What is implied? A young priest should not recite the priestly blessings until he grows a full beard.1As mentioned in the commentary on Chapter 8, Halachah 11, the expression "grows a full beard" is a primarily measure of age, whether the person actually grows a beard or not.
The Shulchan Aruch (Orach Chayim 128:34), based on Tosafot, Chulin 24b, states:
A minor who has not manifested signs of physical maturity should not recite the priestly blessing alone. However, he may recite the blessing together with his brethren, the priests, to learn and become educated.If he has manifested signs of physical maturity, he may recite the priestly blessing even while alone. However, he should do so only as a temporary measure, and not as a fixed practice, until he grows a full beard.
Intoxication: - The Hebrew יין literally means wine. The Magen Avraham 128:55 notes that the Rambam speaks only about wine and does not mention other alcoholic beverages. Accordingly, he explains that a person who becomes drunk from other alcoholic beverages may recite the priestly blessing, unless he is so drunk that he has no control of himself.
It is significant that in Chapter 4, Halachah 17, when speaking about the prohibition against an intoxicated person praying, the Rambam states: "A person who is drunk should not pray.... When is a person considered drunk? When he cannot speak before a king." See also Hilchot Bi'at HaMikdash 1:1-2, where the Rambam describes the prohibition against serving in the Temple while intoxicated and mentions, albeit with differences between them, both a person who drank wine and one who became intoxicated from other alcoholic beverages.
The Magen Avraham's decision is not accepted by all authorities. (See Mishnah Berurah 128:141.)

Intoxication: What is implied? A [priest] who drank a revi'it of wine2This is the minimum measure of wine that is considered to be able to influence a person's behavior. at one time should not recite the priestly blessings until the effects of the wine wear off.3Hilchot Bi'at HaMikdash 1:5 states that if a person drank only a revi'it of wine, it is assumed that the wine's effects have worn off if he sleeps a little or walks a mil. [This restriction was imposed] because an association was established between [reciting the priestly] blessing and service [in the Temple].4as mentioned in the previous halachah.
Should [a priest] drink5only a revi'it of wine on two different occasions6i.e., interrupting slightly between drinking the entire revi'it or mix a small amount of water in it, he is permitted [to recite the priestly blessings].7and serve in the Temple (Hilchot Bi'at HaMikdash 1:1). If he drank more than a revi'it, even though it was mixed with water or even though he drank it intermittently, he should not recite the priestly blessings until the effects of the wine wear off.8In this instance, Hilchot Bi'at HaMikdash 1:5 states that sleeping or walking a mil is not sufficient to remove the effects of the wine, and one must wait until no signs of intoxication remain.
Because of the prohibition against reciting the priestly blessing while intoxicated, it is customary on Simchat Torah in Ashkenazic communities to recite the priestly blessing in the morning service and not during Musaf.

How much is a revi'it?9Interestingly, although the Rambam also mentions a revi'it in Chapter 2, Halachah 17, he chooses to define its volume here. [The volume of an area] two fingerbreadths by two fingerbreadths and two and seven tenths of a fingerbreadth high.10In modern measure, a revi'it is 86.4 milliliters according to Shiurei Torah, and 149.3 milliliters according to the Chazon Ish. Whenever the term "finger" is mentioned as a measure throughout the entire Torah, it refers to a thumbbreadth.11See Hilchot Sefer Torah 9:9. In modern measure, a thumbbreadth is 2 centimeters according to Shiurei Torah, and 2.4 centimeters according to the Chazon Ish. The thumb is called bohen yad [in the Torah].12See Leviticus 8:23, 14:14.

הלכה ה
טֻמְאַת הַיָּדַיִם כֵּיצַד. כֹּהֵן שֶׁלֹּא נָטַל אֶת יָדָיו לֹא יִשָּׂא אֶת כַּפָּיו אֶלָּא נוֹטֵל אֶת יָדָיו עַד הַפֶּרֶק כְּדֶרֶךְ שֶׁמְּקַדְּשִׁין לַעֲבוֹדָה וְאַחַר כָּךְ מְבָרֵךְ שֶׁנֶּאֱמַר (תהילים קלד ב) ״שְׂאוּ יְדֵכֶם קֹדֶשׁ וּבָרַכוּ אֶת יְיָ׳‎״. וְהֶחָלָל אֵינוֹ נוֹשֵׂא אֶת כַּפָּיו לְפִי שֶׁאֵינוֹ בְּכִהוּנוֹ:
כסף משנה
5.
The ritual impurity of [the priest's] hands: What is implied? A priest who did not wash his hands should not recite the priestly blessing.1In his Kessef Mishneh, Rav Yosef Karo notes that in contrast to Chapter 4, Halachah 2, which mentions "the purification of the hands," here, the Rambam refers to "ritual impurity." He maintains that this choice of language was intended to imply that if a priest washed his hands in the morning, he need not wash them a second time unless they have become ritually impure. He also quotes a responsum of Rav Avraham, the Rambam's son, who explicitly states that a priest may rely on his morning washing.
Nevertheless, in his Shulchan Aruch (Orach Chayim 128:6), Rav Yosef Karo quotes the opinion of Rashi and Tosafot (Sotah 39a), who require the priests to have their hands washed a second time as an additional measure of holiness.
Rather, he should wash his hands2The Zohar (Vol. III, 146b) states that the Levites should wash the priests' hands. Since the Levites are themselves holy (Numbers 8:18), it is proper that they be the ones who convey this added holiness upon the priests. The Shulchan Aruch (loc. cit.) also mentions this practice. to the wrist,3Note our commentary Chapter 4, Halachah 2. as is done when sanctifying the hands for the service in the Temple,4See Hilchot Bi'at HaMikdash, Chapter 5. as [Psalms 134:2] states: "Raise up your hands [in] holiness and bless God."
A5The Targum to this verse also stresses its connection to the recitation of the priestly blessing. challal6a person born from relations between a priesta person born from relations between a priest and a divorcee or any other woman who he may not marry (see Leviticus 21:7), and, according to Rabbinic Law, a person born from a marriage between a priest and a woman who has undergone chalitzah. and a divorcee or any other woman who he may not marry (see Leviticus 21:7), and, according to Rabbinic Law, a person born from a marriage between a priest and a woman who has undergone chalitzah. does not recite the priestly blessing, for he is not a priest.7See Hilchot Issurei Bi'ah 19:14, where the Rambam says: "A challal is just like any other non-priest." The Pri Chadash writes that if a challal ascends to bless the people, he should be forced to descend.

הלכה ו
כֹּהֵן שֶׁלֹּא הָיָה לוֹ דָּבָר מִכָּל אֵלּוּ הַדְּבָרִים הַמּוֹנְעִין נְשִׂיאַת כַּפַּיִם אַף עַל פִּי שֶׁאֵינוֹ חָכָם וְאֵינוֹ מְדַקְדֵּק בְּמִצְוֹת אוֹ שֶׁהָיוּ הַבְּרִיּוֹת מְרַנְּנִים אַחֲרָיו אוֹ שֶׁלֹּא הָיָה מַשָּׂאוֹ וּמַתָּנוֹ בְּצֶדֶק הֲרֵי זֶה נוֹשֵׂא אֶת כַּפָּיו וְאֵין מוֹנְעִין אוֹתוֹ לְפִי שֶׁזּוֹ מִצְוַת עֲשֵׂה עַל כָּל כֹּהֵן וְכֹהֵן שֶׁרָאוּי לִנְשִׂיאַת כַּפַּיִם וְאֵין אוֹמְרִים לְאָדָם רָשָׁע הוֹסֵף רֶשַׁע וְהִמָּנַע מִן הַמִּצְוֹת:
כסף משנה
6.
A priest who does not have any of the factors which hinder the recitation of the priestly blessings mentioned above1in the previous five halachot. should recite the priestly blessing, even though he is not a wise man or careful in his observance of the mitzvot. [This applies] even though the people spread unwholesome gossip about him,2i.e., he is suspected of sinning. or his business dealings are not ethical.3Based on Bechorot 45a, the Shulchan Aruch (Orach Chayim 128:40,41) adds that a priest who violates the specific mitzvot associated with the priesthood (the forbidden sexual relations mentioned in Leviticus 21:7 and the prohibitions against contracting impurity stemming from a corpse) may not recite the priestly blessings.
He should not be prevented from [reciting the priestly blessings] - even though he has not repented for his transgressions

He should not be prevented from [reciting the priestly blessings] because [reciting these blessings] is a positive mitzvah incumbent on each priest who is fit to recite them.4From the Rambam's statements, it appears that the disqualifying factors mentioned above remove the mitzvah entirely from a priest. We do not tell a wicked person: Increase your wickedness [by] failing to perform mitzvot.5In other places, as well, we see the Rambam urging people to encourage the nonobservant to perform mitzvot. Note the conclusion of Iggeret HaShmad:
It is not fitting to push away or despise those who violate the Sabbath. Rather one should draw them close and encourage them to perform mitzvot.... Even if a person willingly sins, when he comes to the synagogue to pray, he should be accepted and not treated with disrespect.The Rabbis have based [this approach on the interpretation of] Solomon's words (Proverbs 6:30 "Do not scorn the thief when he steals" - i.e., do not scorn the sinners of Israel when they come discreetly to steal mitzvot.

הלכה ז
וְאַל תִּתְמַהּ וְתֹאמַר וּמַה תּוֹעִיל בִּרְכַּת הֶדְיוֹט זֶה. שֶׁאֵין קִבּוּל הַבְּרָכָה תָּלוּי בַּכֹּהֲנִים אֶלָּא בְּהַקָּדוֹשׁ בָּרוּךְ הוּא שֶׁנֶּאֱמַר (במדבר ו כז) ״וְשָׂמוּ אֶת שְׁמִי עַל בְּנֵי יִשְׂרָאֵל וַאֲנִי אֲבָרַכֶם״. הַכֹּהֲנִים עוֹשִׂים מִצְוָתָן שֶׁנִּצְטַוּוּ בָּהּ וְהַקָּדוֹשׁ בָּרוּךְ הוּא בְרַחֲמָיו מְבָרֵךְ אֶת יִשְׂרָאֵל כְּחֶפְצוֹ:
כסף משנה
7.
Do not wonder: "What good will come from the blessing of this simple person?" for the reception of the blessings is not dependent on the priests, but on the Holy One, blessed be He,1The Jerusalem Talmud, Gittin 5:9 relates:
Do not say: "So and so is an adulterer... how can he bless me?"God replies: "Is it he that is blessing you? I'm the one who is blessing you."
as [Numbers 6:27] states: "And they shall set My name upon the children of Israel, and I shall bless them."2In his commentary on the Torah, the Rashbam emphasizes that the text of priestly blessing itself express this point, stating, "May God bless you..., May God shine..., May God turn..." The priests perform the mitzvah with which they were commanded,3reciting the blessings and God, in His mercies, will bless Israel as He desires.

הלכה ח
עַם שֶׁהֵם אֲחוֹרֵי הַכֹּהֲנִים אֵינָם בִּכְלַל הַבְּרָכָה. וְהָעוֹמְדִים מִצִּדֵּיהֶן הֲרֵי הֵם בִּכְלַל הַבְּרָכָה. וְאִם הָיְתָה מְחִצָּה בֵּין הַכֹּהֲנִים וּבֵין הַמִּתְבָּרְכִים אֲפִלּוּ הִיא חוֹמָה שֶׁל בַּרְזֶל הוֹאִיל וּפְנֵיהֶם מוּל פְּנֵי הַכֹּהֲנִים הֲרֵי הֵם בִּכְלַל הַבְּרָכָה:
כסף משנה
8.
The people standing behind the priests are not included in the blessing.1By standing behind the priests, they show that the blessing is not important to them. Hence, they are not included (Rashi, Sotah 38b). Also, as mentioned in Chapter 14, Halachah 11, the priestly blessing must be recited while the priests are standing face to face with those being blessed (Shulchan Aruch HaRav 128:37). Those standing at their sides2even those who are standing parallel to the place of the priests are included in the blessing. [Even] if there is a partition3even an iron wall - Sotah (loc. cit.) states: "Even an iron divider cannot separate between Israel and their Father in heaven." - even an iron wall - between the priests and the people who are being blessed, since they are facing the priests,4The Be'ur Halachah explains that the people who are standing to the sides of the priests, but before them, should face the heichal. In principle, those who are standing parallel to the priests should turn to the side and face the priests. However, since it is not proper that people standing next to each other in the synagogue should face different directions, they need not shift the positions of their feet. It is sufficient for them to tilt their heads slightly towards the priests. they are included in the blessing.5As the Rambam mentions in the following halachah, even people who do not attend the synagogue can be included in the priestly blessing.

הלכה ט
נְשִׂיאַת כַּפַּיִם בַּעֲשָׂרָה וְכֹהֲנִים מִן הַמִּנְיָן. בֵּית הַכְּנֶסֶת שֶׁכֻּלָּן כֹּהֲנִים כֻּלָּם נוֹשְׂאִים אֶת כַּפֵּיהֶם. וּלְמִי הֵם מְבָרְכִים לְאַחֵיהֶם שֶׁבַּצָּפוֹן וְלַאֲחֵיהֶם שֶׁבַּדָּרוֹם. וּמִי עוֹנֶה אַחֲרֵיהֶם אָמֵן הַנָּשִׁים וְהַטַּף. וְאִם נִשְׁאֲרוּ שָׁם עֲשָׂרָה כֹּהֲנִים יוֹתֵר עַל אֵלּוּ שֶׁעָלוּ לַדּוּכָן הָעֲשָׂרָה עוֹנִין אָמֵן וְהַשְּׁאָר מְבָרְכִין:
כסף משנה
9.
The priestly blessing is recited [only] when ten people [are present].1The priestly blessing is included among "the holy matters" that require a minyan. See Chapter 8, Halachot 4-6. The priests can be included in that number.2i.e., even if there will not be ten people to respond "Amen," the priestly blessing can be recited.
If [the congregation in a particular] synagogue are all priests, they should all3Even though there will no one to read the words of the blessings to them, as mentioned in Chapter 14, Halachah 3. The question of whether the chazan should also recite the priestly blessing is discussed in the following halachah. recite the priestly blessing.4Unless there are a minyan of priests to respond "Amen," it is preferable that they all recite the blessings and none respond.
Who should they bless? Their brethren in the north and the south - i.e., those outside the synagogue. Even though they were unable to attend the synagogue, since they were prevented by forces beyond their control, they are included within the blessing.
The Rambam's statements are taken from Sotah 38b and the Jerusalem Talmud, Berachot 5:4. However, the Rambam's choice of phraseology is more restrictive, mentioning only "the people in the north and the south," while these sources state, "their brethren in the fields."
According to his grandson, Rav Yitzchak HaNagid, this restriction was intentional. Since in the Rambam's time the Jews lived mostly to the east or west of Jerusalem, in most synagogues the heichal would be pointed in that direction, and thus, depending on the location of the synagogue, the people standing in one of these directions would be standing behind the priests. Therefore, they would not be included in the blessing.
Other authorities (e.g., the Shulchan Aruch, Orach Chayim 128:25) quote the text in the Babylonian Talmud without making any restrictions.
Who should they bless? Their brethren in the north and the south. Who will respond "Amen" to their [blessings]? The women and the children.5The Mishnah Berurah 128:99 states that even if there are no women or children present to answer "Amen," the blessing may be recited. If more than ten priests remain besides those who ascend to the duchan, these ten [priests] respond "Amen"6i.e., if there are twelve priests, two recite the blessings and ten respond "Amen," so that there will be a minyan responding "Amen." and the remainder of the priests recite the blessings.7The Shulchan Aruch HaRav 128:33 states that in such an instance, the chazan should not call out "Kohanim," since, according to many opinions, if the priests are not called to recite the blessings, they are not obligated to do so. Thus, the priests who did not recite the blessings will not be considered negligent in their fulfillment of the mitzvah.

הלכה י
צִבּוּר שֶׁלֹּא הָיָה בָּהֶן כֹּהֵן אֶלָּא שְׁלִיחַ צִבּוּר לְבַדּוֹ לֹא יִשָּׂא אֶת כַּפָּיו. וְאִם הָיְתָה הַבְטָחָתוֹ שֶׁהוּא נוֹשֵׂא אֶת כַּפָּיו וְחוֹזֵר לִתְפִלָּתוֹ רַשַּׁאי. וְאִם אֵין לָהֶם כֹּהֵן כְּלָל כְּשֶׁיַּגִּיעַ שְׁלִיחַ צִבּוּר לְשִׂים שָׁלוֹם אוֹמֵר אֱלֹהֵינוּ וֵאלֹהֵי אֲבוֹתֵינוּ בָּרְכֵנוּ בַּבְּרָכָה הַמְשֻׁלֶּשֶׁת בַּתּוֹרָה הַכְּתוּבָה עַל יְדֵי משֶׁה עַבְדְּךָ הָאֲמוּרָה מִפִּי אַהֲרֹן וּבָנָיו כֹּהֲנִים עַם קְדוֹשֶׁךָ כָּאָמוּר (במדבר ו כד) ״יְבָרֶכְךָ יְיָ׳‎ וְיִשְׁמְרֶךָ״ (במדבר ו כה) ״יָאֵר יְיָ׳‎ פָּנָיו אֵלֶיךָ וִיחֻנֶּךָּ״ (במדבר ו כו) ״יִשָּׂא יְיָ׳‎ פָּנָיו אֵלֶיךָ וְיָשֵׂם לְךָ שָׁלוֹם״ (במדבר ו כז) ״וְשָׂמוּ אֶת שְׁמִי עַל בְּנֵי יִשְׂרָאֵל וַאֲנִי אֲבָרַכֶם״. וְאֵין הָעָם עוֹנִין אָמֵן. וּמַתְחִיל וְאוֹמֵר שִׂים שָׁלוֹם:
כסף משנה
10.
When there is no priest in the community other than the leader of the congregation,1The Shulchan Aruch, Orach Chayim 128:20, states that if other priests are present, a priest serving as the chazan should never recite the priestly blessing. The Pri Chadash takes issue with this decision, and allows him to recite the priestly blessings if he is confident that he will not err. he should not recite the priestly blessings.2lest he become confused after completing the priestly blessing and be unable to complete the Shemoneh Esreh (Berachot 34b). If he is sure that he can recite the priestly blessings and return to his prayers [without becoming confused],3Note Shulchan Aruch HaRav 128:32 and the Mishnah Berurah 128:76, which state that at present, since the chazan prays from a siddur, he need not worry about being confused and may recite the priestly blessing. he may [recite the priestly blessing].4The Shulchan Aruch (loc. cit.) states that in such a case, the chazan should move from his place slightly during the blessing R'tzey (see the following halachah) and after concluding the blessing Modim, ascend to the duchan and recite the priestly blessing.
If there are no priests present at all - or according to Ashkenazic custom, in all services when the priestly blessing would be recited other than the Musaf service of the festivals.

If there are no priests present at all, when the leader of the congregation reaches [the blessing] Sim shalom,5See the Commentary on Chapter 14, Halachah 4, for an explanation of the connection between the blessing Sim shalom and the priestly blessings. he recites [the following prayer]:
Our6to commemorate the recitation of these blessings. God and God of our fathers, bless us with the threefold blessing written in the Torah by Moses, Your servant, and recited by Aharon and his sons, the priests, Your consecrated people,7Our translation is based on the Mishnah Berurah 127:8, which explains that the intent is that the priests themselves are a "consecrated people." as it is8Numbers 6:24-27 said:

May God bless you and keep you.9May God bless you and keep you. May God shine His countenance upon you and be gracious to you. May God turn His countenance to you and grant you peace.

May God shine His countenance upon you and be gracious to you.

May God turn His countenance to you and grant you peace.

And they shall set My name upon the children of Israel and I will bless them.10The Hagahot Maimoniot explain that the recitation of this verse parallels the prayer recited by the priests after completing the blessings (Chapter 14, Halachah 12). It is Ashkenazic custom not to recite this final verse (Magen Avraham 127:2).
The people do not respond "Amen" to these blessings.11for it is proper to recite "Amen" only after the blessings recited by the priests themselves. The Shulchan Aruch 127:2 suggests reciting ken yehi ratzon - "So may it be Your will." Nevertheless, there are some communities which recite "Amen," based on the Tanya Rabbati 334 and a letter from Rav Hai Gaon. He [resumes his recitation of the Shemoneh Esreh], beginning the recitation of [the blessing] Sim shalom.

הלכה יא
כֹּהֵן שֶׁנָּשָׂא אֶת כַּפָּיו בְּבֵית הַכְּנֶסֶת וְהָלַךְ לְבֵית הַכְּנֶסֶת אַחֵר וּמָצָא צִבּוּר שֶׁמִּתְפַּלְּלִין וְלֹא הִגִּיעוּ לְבִרְכַּת כֹּהֲנִים נוֹשֵׂא יָדָיו לָהֶן וּמְבָרְכָן. וַאֲפִלּוּ כַּמָּה פְּעָמִים בְּיוֹם. כֹּהֵן שֶׁלֹּא עָקַר רַגְלָיו מִמְּקוֹמוֹ לַעֲלוֹת לַדּוּכָן בְּשָׁעָה שֶׁאָמַר שְׁלִיחַ צִבּוּר רְצֵה שׁוּב אֵינוֹ עוֹלֶה בְּאוֹתָהּ תְּפִלָּה. אֲבָל אִם עָקַר רַגְלָיו לַעֲלוֹת אַף עַל פִּי שֶׁלֹּא הִגִּיעַ לַדּוּכָן אֶלָּא אַחַר עֲבוֹדָה הֲרֵי זֶה עוֹלֶה וּמְבָרֵךְ:
כסף משנה
11.
A priest who recited the priestly blessings and went to another synagogue and found the congregation in the midst of prayer, before the [recitation of] the priestly blessings, should bless them.1The Magen Avraham emphasizes that reciting the priestly blessings a second time is not considered to be a transgression of the prohibition of adding to the Torah's commandments. That prohibition is violated when one adds to the blessings themselves (see Chapter 14, Halachah 12), but not when one fulfills the mitzvah a number of times. [He may recite the priestly blessings] several times during the day.2This statement has raised questions among the commentaries. The Kiryat Sefer explains that the priests recite Y'varechecha - the first word of the priestly blessings - directly after concluding the blessing (see Halachah 12) recited before blessing the people, without being prompted by the reader. They take the initiative, so that an interruption is not made between the recitation of the blessing before the performance of a mitzvah and its actual performance.
Study of the Rambam's Commentary on the Mishnah (Berachot, loc. cit.) shows that the Rambam himself had questions about this matter. In the first manuscripts, the Rambam writes that "the leader of the congregation recites Y'varechecha, and the priests read after him." This is also the reading in the popularly published edition of that text. However, in the later manuscripts of the Commentary on the Mishnah (see Rav Kapach's edition of that text), the Rambam changes his mind and states that the priests begin reciting y'varechecha.
In his Beit Yosef (Orach Chayim 128), Rav Yosef Karo mentions these different views, and in his Shulchan Aruch (128:13) rules that the priests begin on their own initiative. The Ramah differs and states that it is Ashkenazic practice that this word is also recited in response to the chazan.

A priest who does not move from his place to ascend to the duchan when the leader of the congregation recites [the blessing] R'tzey3See Chapter 14, Halachah 3. should not ascend [to the duchan] during that prayer service.4This applies even if he was prevented from leaving his place by forces beyond his control (Radbaz, Magen Avraham). However, if he moved [from his place], even though he did not reach the duchan until after the [conclusion of the blessing R'tzey],5Shulchan Aruch HaRav 128:13 and the Mishnah Berurah 128:27 state that even if he reaches the duchan after the chazan completes R'tzey, as long as he reaches there before the priests begin reciting the blessing, he may join them. he may6but he is not obligated to (Mishnah Berurah 128:106). ascend [the duchan] and bless [the people].

הלכה יב
כָּל כֹּהֵן שֶׁאֵינוֹ עוֹלֶה לַדּוּכָן אַף עַל פִּי שֶׁבִּטֵּל מִצְוַת עֲשֵׂה אַחַת הֲרֵי זֶה כְּעוֹבֵר עַל שָׁלֹשׁ עֲשֵׂה שֶׁנֶּאֱמַר (במדבר ו כג) ״כֹּה תְבָרַכוּ אֶת בְּנֵי יִשְׂרָאֵל״ (במדבר ו כג) ״אָמוֹר לָהֶם״ (במדבר ו כז) ״וְשָׂמוּ אֶת שְׁמִי״. וְכָל כֹּהֵן שֶׁאֵינוֹ מְבָרֵךְ אֵינוֹ מִתְבָּרֵךְ וְכָל כֹּהֵן הַמְבָרֵךְ מִתְבָּרֵךְ שֶׁנֶּאֱמַר (בראשית יב ג) ״וַאֲבָרַכָה מְבָרְכֶיךָ״:
סְלִיקוּ הִלְכוֹת תְּפִלָה בְּסִיַּעְתָּא דִּשְׁמַיָּא
כסף משנה
12.
Any priest who does not ascend to the duchan1even though he neglects [the performance] of [only] one commandment - is considered as if he violated three positive commandments, as Numbers 6:23-27 states: “This is how you shall bless the children of Israel,” “Say to them,” “And you shall set My name...” - The Rambam's statements are based on Sotah 38b. There, the Talmud states that one “violates three positive commandments.” The Rambam amends that statement, explaining that although there is only one commandment for the priests to bless the people, the Torah mentioned the commandment in three different ways to emphasize the importance of its fulfillment. Thus, the failure to bless the people is considered as nullifying the observance of three commands.
In Sefer HaMitzvot (Shoresh 9), the Rambam cites this teaching as a classic example of a fundamental principle regarding the reckoning of the 613 mitzvot. Though the Talmud often states that many mitzvot are involved in the performance or transgression of a particular commandment, this does not mean that the mitzvah should be counted as more than one mitzvah when calculating the 613 mitzvot of the Torah. Rather, the Talmud means to say that the performance of this mitzvah is considered as important as if many mitzvot were involved.
- even though he neglects [the performance] of [only] one commandment - is considered as if he violated three positive commandments, as [Numbers 6:23-27] states: "This is how you shall bless the children of Israel," "Say to them," "And you shall set My name..."
Any priest who does not recite the priestly blessing will not be blessed, and any priest who blesses [the people] will be blessed, as [Genesis 12:3] states: "And I will bless those who bless you."2Chulin 49a quotes a difference of opinion between Rabbi Akiva and Rabbi Yishmael. Rabbi Akiva's statements are quoted by the Rambam, while Rabbi Yishmael explains that the blessing for the priests is derived from Numbers 6:27: “And you will set My name upon the children of Israel and I will bless them.” “The priests bless the Jews and God blesses the priests,... together with the Jews” (Rashi).
By quoting the verse from Genesis, “and I will bless those who bless you,” Rabbi Akiva emphasizes that the blessings bestowed upon the priests - as well as the blessing conveyed by the priests - stem from God's infinite goodness (Likkutei Sichot, Vol. 10).
Blessed be the Merciful One who grants assistance.

אהבה הלכות תפילה וברכת כהנים פרק טו
Ahavah Tefilah and Birkas Kohanim Chapter 15