Halacha

הלכה א
אֵי זוֹ הִיא חֲלָלָה זוֹ שֶׁנּוֹלִדָה מֵאִסּוּר כְּהֻנָּה. וְכֵן אַחַת מִן הַנָּשִׁים הָאֲסוּרוֹת לִכְהֻנָּה שֶׁנִּבְעֲלָה לְכֹהֵן נִתְחַלְּלָה. אֲבָל הַכֹּהֵן עַצְמוֹ שֶׁעָבַר הָעֲבֵרָה לֹא נִתְחַלֵּל:
כסף משנה
1.
What is meant by a challalah? [A woman] born from [relations] forbidden to the priesthood.1I.e., the women mentioned in Chapter 17, Halachah 1. Similarly, any woman who is forbidden to the priesthood who engaged in relations with a priest becomes a challalah. A priest who commits a transgression himself, however, is not deemed a challal.2The fact that he engaged in forbidden relations does not detract from the essential holiness endowed to him by his priestly lineage.

הלכה ב
וּבֵין שֶׁנִּבְעֲלָה בְּאֹנֶס אוֹ בִּשְׁגָגָה [בֵּין כְּדַרְכָּהּ בֵּין שֶׁלֹּא כְּדַרְכָּהּ] מִשֶּׁהֶעֱרָה בָּהּ נִתְחַלְּלָה. וְהוּא שֶׁיִּהְיֶה כֹּהֵן בֶּן תֵּשַׁע שָׁנִים וְיוֹם אֶחָד וָמַעְלָה וְתִהְיֶה זוֹ הָאֲסוּרָה לוֹ בַּת שָׁלֹשׁ שָׁנִים וְיוֹם אֶחָד וָמַעְלָה:
כסף משנה
2.
[The above applies] whether she engaged in relations by coercion or inadvertently3For the spiritual blemish brought about by the forbidden relations has an effect regardless of her intent or lack of it. or whether it was vaginal or anal intercourse, as soon as the male organ enters her, she becomes a challalah. [This applies] provided the priest is nine years of age or older and the woman forbidden him is three years of age or older.4For only when the male and the female are these respective ages are their relations considered significant.

הלכה ג
כֵּיצַד. כֹּהֵן בֶּן תֵּשַׁע שָׁנִים וְיוֹם אֶחָד שֶׁבָּא עַל הַגְּרוּשָׁה אוֹ עַל הַזּוֹנָה. וְכֹהֵן גָּדוֹל שֶׁבָּא עֲלֵיהֶן אוֹ עַל הָאַלְמָנָה אוֹ שֶׁנָּשָׂא בְּעוּלָה וּבָא עָלֶיהָ הֲרֵי אֵלּוּ נִתְחַלְּלוּ לְעוֹלָם. וְאִם הוֹלִיד מִמֶּנָּה בֶּן בֵּין זֶה שֶׁחִלְּלָהּ בֵּין כֹּהֵן אַחַר הַוָּלָד חָלָל. אֲבָל כֹּהֵן שֶׁקִּדֵּשׁ אִשָּׁה מֵאִסּוּרֵי כְּהֻנָּה וְנִתְאַלְמְנָה אוֹ נִתְגָּרְשָׁה מִן הָאֵרוּסִין לֹא נִתְחַלְּלָה. וְאִם נִשֵּׂאת אַף עַל פִּי שֶׁלֹּא נִבְעֲלָה נִתְחַלְּלָה שֶׁכָּל נְשׂוּאָה בְּחֶזְקַת בְּעוּלָה הִיא אַף עַל פִּי שֶׁנִּמְצֵאת בְּתוּלָה:
כסף משנה
3.
What is implied? When a priest who is nine years old engages in relations with a divorcee or with a zonah or a High Priest enters into relations with such women or with a widow, or marries a non-virgin and enters into relations with her,5Note the contrast to the following halachah. Although a non-virgin is forbidden only on the basis of a positive commandment (Chapter 17, Halachah 13), offspring from such a relationship are challalim. these women become challalot for all time. If they conceive a child from such relations, whether from relations with the priest who caused them to be deemed a challalah or whether with another priest, the offspring are challalim.
When, however, a priest consecrates a woman who is forbidden to the priesthood and she is widowed or divorced from the consecration, she does not become a challalah.6Needless to say, a divorcee may not marry a priest. The Rambam is emphasizing that if she is divorced, in addition to the prohibition of a divorcee, she is also prohibited as a challalah. If she marries, even if she does not engage in relations, she becomes a challalah even if it is discovered that she is a virgin.7For as Ketubot 11a states, a woman who is divorced after marriage is considered as if she has engaged in relations. The Chelkat Mechokek 7:23 and the Beit Shmuel 7:36 discuss this ruling, mentioning views that differ slightly.

הלכה ד
כֹּהֵן גָּדוֹל שֶׁנָּשָׂא בּוֹגֶרֶת אוֹ מֻכַּת עֵץ לֹא חִלְּלָהּ. וְכֵן אִם בַּעַל בְּעוּלָה בְּלֹא נִשּׂוּאִין לֹא חִלְּלָהּ:
כסף משנה
4.
When a High Priest marries a woman past majority or one who lost her signs of virginity through means other than intercourse, she does not become a challalah.8For after the fact, he is allowed to remain married to such a woman, as stated in Chapter 17, Halachah 15. Similarly, if he enters into relations with a non-virgin outside the context of marriage, she does not become a challalah.9For the prohibition forbidding her to him applies only within the context of marriage (Chapter 17, Halachah 2). Although he performs a transgression for entering into intimacy without the intent of marriage (see Hilchot Ishut 1:4), that prohibition is not restricted to the priesthood and offspring are deemed challalim, only when the prohibition against the relations is exclusive to the priesthood.

הלכה ה
כֹּהֵן הַבָּא עַל עֶרְוָה מִן הָעֲרָיוֹת חוּץ מִנִּדָּה אוֹ עַל אַחַת מֵחַיָּבֵי לָאוִין הַשָּׁוִין בְּכָל עֲשֵׂה אוֹתָהּ זוֹנָה כְּמוֹ שֶׁבֵּאַרְנוּ. חָזַר וּבָא עָלֶיהָ בִּיאָה שְׁנִיָּה בֵּין הוּא בֵּין כֹּהֵן אַחֵר נַעֲשֵׂית חֲלָלָה וְזַרְעוֹ מִמֶּנָּה חֲלָלִים. לְפִיכָךְ כֹּהֵן שֶׁבָּא עַל זְקוּקָה לְיָבָם וְנִתְעַבְּרָה מִבִּיאָה רִאשׁוֹנָה הַוָּלָד כָּשֵׁר לְפִי שֶׁאֵינָהּ מֵאִסּוּרֵי כְּהֻנָּה וְנַעֲשֵׂית זוֹנָה. חָזַר וּבָא עָלֶיהָ בִּיאָה שְׁנִיָּה וְנִתְעַבְּרָה וְיָלְדָה הִיא חֲלָלָה וּוְלָדָהּ חָלָל לְפִי שֶׁהוּא מֵאִסּוּרֵי כְּהֻנָּה:
כסף משנה
5.
When a priest engages in relations with one of the women forbidden as an ervah with the exception of a woman in the niddah state or with one of the woman who is forbidden because of a negative commandment that is universally applicable, he causes her to be deemed a zonah, as explained.10Chapter 18, Halachah 1. If he - or another priest - engage in relations with her a second time, she becomes a challalah11Since she became a zonah, the prohibition against relations with her is exclusive to the priesthood. and her offspring from [a priest] are challalim.
Accordingly, if a priest engages in relations with a woman who is obligated to undergo yibbum and she conceived from their first relations, the offspring is acceptable to marry into the priesthood. [The rationale is that] the prohibition [against relations with such a woman] is not restricted to the priesthood. She becomes a zonah as we explained.12Chapter 18, Halachah 2. For the relations do involve a transgression. If he engaged in relations with her a second time and she conceived and gave birth, she becomes a challalah and her offspring are challalim, for [these relations]13I.e., relations with a zonah. are forbidden exclusively to the priesthood.

הלכה ו
וְכֵן כֹּהֵן הַבָּא עַל הַגִּיֹּרֶת וְהַמְשֻׁחְרֶרֶת חֲלָלָה וְזַרְעוֹ מִמֶּנָּה חֲלָלִים. כֹּהֵן הַבָּא עַל הַנִּדָּה הַוָּלָד כָּשֵׁר וְאֵינוֹ חָלָל שֶׁאֵין אִסּוּר הַנִּדָּה מְיֻחָד בְּכֹהֲנִים אֶלָּא שָׁוֶה בַּכּל:
כסף משנה
6.
Similarly, when a priest engages in relations with a convert or a freed maid-servant, he causes her to become a challalah14For they are forbidden exclusively to the priesthood, as stated in Chapter 18, Halachah 3. and his offspring from her are challalim.15Even if they are conceived during the first time the couple engage in relations [Shulchan Aruch (Even HaEzer 7:14)]. The rationale is that even before the priest engages in relations with such women, they are deemed as zonot. When a priest engages in relations with a woman in the niddah state, the offspring are acceptable and are not challalim. For the prohibition [against relations with] a woman in the niddah state is universally applicable and is not exclusive to the priesthood.

הלכה ז
כֹּהֵן שֶׁנָּשָׂא גְּרוּשָׁה מְעֻבֶּרֶת בֵּין מִמֶּנּוּ בֵּין מֵאַחֵר וְיָלְדָה כְּשֶׁהִיא חֲלָלָה הַוָּלָד כָּשֵׁר שֶׁהֲרֵי לֹא בָּא מִטִּפַּת עֲבֵרָה:
כסף משנה
7.
When a priest marries a divorcee who is pregnant - whether with his child or that of another man - and she gives birth after she became a challalah, the child is acceptable, for it was not conceived from forbidden seed.16As Kiddushin 77a states, the determination of whether a child is deemed as a challal or not depends on whether it was conceived through a transgression or not. The mother's status at the time of birth is not significant.

הלכה ח
כְּבָר בֵּאַרְנוּ שֶׁהַחֲלוּצָה אֲסוּרָה לְכֹהֵן מִדִּבְרֵיהֶם. לְפִיכָךְ כֹּהֵן שֶׁבָּא עַל הַחֲלוּצָה הֲרֵי זוֹ חֲלָלָה וְזַרְעָהּ מִכֹּהֵן חֲלָלִים וְהַכּל מִדִּבְרֵיהֶן. אֲבָל כֹּהֵן שֶׁבָּא עַל אַחַת מֵהַשְּׁנִיּוֹת הִיא כְּשֵׁרָה וְזַרְעוֹ מִמֶּנָּה כְּשֵׁרִים. שֶׁאִסּוּר הַשְּׁנִיּוֹת אִסּוּר הַשָּׁוֶה בַּכּל הוּא וְאֵינוֹ מְיֻחָד בְּכֹהֲנִים:
כסף משנה
8.
We have already explained,17In Chapter 17, Halachah 7. that a woman who has undergone chalitzah is forbidden to a priest by Rabbinic decree. Therefore, when a priest engages in relations with such a woman, she becomes a challalah and her offspring, challalim. All of this is based on Rabbinic decree. When, by contrast, a priest engages in relations with one of the shniot,18Relatives forbidden by Rabbinic decree as listed in Hilchot Ishut 1:6. she is acceptable19See Chapter 18, Halachah 4. and his descendants from her are acceptable, for these prohibitions are universally applicable and are not exclusive to the priesthood.

הלכה ט
כֹּהֵן שֶׁבָּא עַל סְפֵק זוֹנָה כְּגוֹן סְפֵק גִּיֹּרֶת אוֹ מְשֻׁחְרֶרֶת. אוֹ שֶׁבָּא עַל סְפֵק גְּרוּשָׁה. וְכֵן כֹּהֵן גָּדוֹל שֶׁבָּא עַל סְפֵק אַלְמָנָה הֲרֵי זוֹ סְפֵק חֲלָלָה וּוְלָדָהּ סְפֵק חָלָל:
כסף משנה
9.
When a priest engages in relations with a woman whose status as a zonah is questionable, e.g., a woman concerning whose status as a convert or as a freed maid-servant is questionable, when he engages in relations with a woman whose status as a divorcee is questionable,20The Shulchan Aruch (Even HaEzer 7:20) quotes the Rambam's ruling. The Tur and the Rama state that the same laws apply to a woman who underwent a chalitzah ceremony of questionable validity. Based on the distinction between such a woman and a woman whose status is a divorcee is questionable which the Rambam makes in Chapter 17, Halachah 7, the Beit Shmuel 7:40 maintains that the Rambam would not accept such an addition. or a High Priest engages in relations with a woman whose status as a widow is questionable,21See Chapter 17, Halachah 12. the woman is deemed as a challalah of questionable status and her offspring are considered challalim of questionable status.

הלכה י
נִמְצְאוּ הַחֲלָלִים שְׁלֹשָׁה. חָלָל מִן הַתּוֹרָה. וְחָלָל מִדִּבְרֵיהֶם. וּסְפֵק חָלָל. וְכָל סְפֵק חָלָל נוֹתְנִין עָלָיו חֻמְרֵי כֹּהֲנִים וְחֻמְרֵי יִשְׂרָאֵל. אֵינוֹ אוֹכֵל בִּתְרוּמָה וְלֹא מִטַּמֵּא לַמֵּתִים וְנוֹשֵׂא אִשָּׁה הָרְאוּיָה לְכֹהֵן. וְאִם אָכַל אוֹ נִטְמָא אוֹ נָשָׂא גְּרוּשָׁה מַכִּין אוֹתוֹ מַכַּת מַרְדּוּת. וְהוּא הַדִּין בְּחָלָל שֶׁל דִּבְרֵיהֶם. אֲבָל חָלָל שֶׁל תּוֹרָה הַוַּדַּאי הֲרֵי הוּא כְּזָר וְנוֹשֵׂא גְּרוּשָׁה וּמִטַּמֵּא לַמֵּתִים שֶׁנֶּאֱמַר (ויקרא כא א) "אֱמֹר אֶל הַכֹּהֲנִים בְּנֵי אַהֲרֹן". אַף עַל פִּי שֶׁהֵם בְּנֵי אַהֲרֹן עַד שֶׁיִּהְיוּ בְּכִהוּנָם:
כסף משנה
10.
Thus there are three categories of challalim: a challal according to Scriptural Law, a challal according to Rabbinic decree, a person whose status as a challal is a matter of question.
Anyone whose status as a challal is a matter of question must observe the severities incumbent on the priesthood and those incumbent on ordinary Israelites.22Otherwise, there is a possibility that he will be violating prohibitions of Scriptural origin. He may not partake of terumah.23Lest he is an Israelite to whom this is forbidden. See Hilchot Terumah 6:7. He may not become impure due to contact with the dead24Lest he is a priest to whom this is forbidden. and he must marry a woman fit to marry a priest. If he partakes of terumah, becomes impure, or marries a divorcee, he is given stripes for rebellious conduct. The same laws apply to a challal by Rabbinic decree.
When, however, a person is definitely a challal according to Scriptural Law, he is like [any other] non-priest. He may marry a divorcee and become impure due to contact with a corpse. [This is derived from Leviticus 21:1 which] states: "Speak to the priests, the descendants of Aaron." [Implied is that the prohibition that follows25The prohibition against contact with a corpse. does not apply] even to the descendants of Aaron unless they are priests.

הלכה יא
כֹּהֵן זָכָר שֶׁהוּא אָסוּר לִשָּׂא זוֹנָה וַחֲלָלָה אָסוּר בְּגִיֹּרֶת וּמְשֻׁחְרֶרֶת שֶׁהִיא כְּזוֹנָה כְּמוֹ שֶׁבֵּאַרְנוּ. אֲבָל הַכֹּהֶנֶת מֻתֶּרֶת לְהִנָּשֵׂא לְחָלָל וּלְגֵר וְלִמְשֻׁחְרָר שֶׁלֹּא הֻזְהֲרוּ כְּשֵׁרוֹת לְהִנָּשֵׂא לִפְסוּלִין שֶׁנֶּאֱמַר (ויקרא כא א) "בְּנֵי אַהֲרֹן" וְלֹא בְּנוֹת אַהֲרֹן. נִמְצָא הַגֵּר מֻתָּר לִשָּׂא מַמְזֶרֶת וְלִשָּׂא כֹּהֶנֶת:
כסף משנה
11.
A male priest who is forbidden to marry a zonah and a challalah is forbidden to marry a female convert and freed maid-servant for they are equivalent to zonot as we explained.26Chapter 18, Halachah 3. A woman of the priestly family, however, is permitted to marry a challal, a convert, or a freed servant. For women of acceptable lineage were not forbidden against marrying men of unacceptable lineage.27I.e., those forbidden to the priesthood (Maggid Mishneh). See, however, Halachah 21 and notes. [This is derived from the phrase "the descendants" [- literally, the sons -] of Aaron," i.e., sons and not daughters. Thus a convert is permitted to marry a female mamzer28See Chapter 15, Halachah 7. and also, the daughter of a priest.

הלכה יב
גֵּרִים וּמְשֻׁחְרָרִים שֶׁנָּשְׂאוּ אֵלּוּ מֵאֵלּוּ וְהוֹלִידוּ בַּת אֲפִלּוּ לְאַחַר כַּמָּה דּוֹרוֹת הוֹאִיל וְלֹא נִתְעָרֵב בָּהֶן זֶרַע יִשְׂרָאֵל הֲרֵי אוֹתָהּ הַבַּת אֲסוּרָה לְכֹהֵן. וְאִם נִשֵּׂאת לֹא תֵּצֵא הוֹאִיל וְהוֹרָתָהּ וְלֵדָתָהּ בִּקְדֻשָּׁה. אֲבָל גֵּר אוֹ מְשֻׁחְרָר שֶׁנָּשָׂא בַּת יִשְׂרָאֵל אוֹ יִשְׂרָאֵל שֶׁנָּשָׂא גִּיֹּרֶת אוֹ מְשֻׁחְרֶרֶת בִּתּוֹ כְּשֵׁרָה לִכְהֻנָּה לְכַתְּחִלָּה:
כסף משנה
12.
When converts and/or freed servants marry among themselves and give birth to a daughter - even after several generations - this daughter is forbidden to marry a priest,29Kiddushin 78b states that after the destruction of the Temple, the priests accepted this stringency upon themselves. for the seed of a native-born Jew has not intermingled with them. If one married such a woman, she need not be divorced since she was both conceived and born in holiness.30Note the Beit Yosef (Even HaEzer 7), the Chelkat Mechokek 7:29 and the Beit Shmuel 7:42 who note that the Rambam requires the girl to be both conceived and born within the Jewish people. When, however, a convert or a freed servant marries a native-born Jewess or a native-born Jew marries a female convert or a freed slave, their daughter is acceptable to marry into the priesthood at the outset.

הלכה יג
גֵּר עַמּוֹנִי שֶׁנָּשָׂא בַּת יִשְׂרָאֵל וְכֵן מִצְרִי שֵׁנִי שֶׁנָּשָׂא בַּת יִשְׂרָאֵל אַף עַל פִּי שֶׁבִּיאָתָם בַּעֲבֵרָה וַהֲרֵי נְשׁוֹתֵיהֶן זוֹנוֹת כְּמוֹ שֶׁבֵּאַרְנוּ בְּנוֹתֵיהֶם כְּשֵׁרוֹת לִכְהֻנָּה לְכַתְּחִלָּה:
כסף משנה
13.
When an Ammonite convert31Who is forbidden to marry a native-born Jewess (Chapter 12, Halachah 18). or a second generation Egyptian convert32Who is likewise forbidden (ibid.:19). marry a native-born Jewess, the intimate relations they share involve a transgression and the women become zonot as we explained.33Chapter 18, Halachah 3. As Yevamot 36a states, the women themselves may not marry a priest, but their daughters may. Nevertheless, their daughters may marry into the priesthood as an initial and preferred option.34For a female Ammonite is permitted and a third generation Egyptian is permitted.

הלכה יד
חָלָל שֶׁנָּשָׂא כְּשֵׁרָה זַרְעוֹ מִמֶּנָּה חֲלָלִים. וְכֵן בֶּן בֶּן בְּנוֹ וַאֲפִלּוּ אַחַר אֶלֶף דּוֹר. שֶׁבֶּן הֶחָלָל הַזָּכָר הוּא חָלָל לְעוֹלָם. וְאִם הָיְתָה בַּת אֲסוּרָה הִיא לִכְהֻנָּה שֶׁהֲרֵי הִיא חֲלָלָה. אֲבָל יִשְׂרָאֵל שֶׁנָּשָׂא חֲלָלָה הַוָּלָד כָּשֵׁר. לְפִיכָךְ אִם הָיְתָה בַּת הֲרֵי זוֹ תִּנָּשֵׂא לִכְהֻנָּה לְכַתְּחִלָּה:
כסף משנה
14.
When a challal marries an acceptable woman, his descendants from her are challalim. This also applies to the son of his son's son35We have not used the term grandson or great grandson, because if a female descendant is involved, the next generation are not challalim. and indeed, even for 1000 generations. For the male son of a challal is a challal for all time. If the offspring is female, she is forbidden to marry into the priesthood, because she is a challalah.
When, however, an Israelite marries a challalah, the offspring are acceptable.36Neither the son, nor the daughter are considered challalim. Therefore if one of the offspring is female, she may marry into the priesthood at the outset.

הלכה טו
כֹּהֲנִים וּלְוִיִּם וְיִשְׂרְאֵלִים מֻתָּרִין לָבוֹא זֶה בָּזֶה. וְהַוָּלָד הוֹלֵךְ אַחַר הַזָּכָר. (לְוִיִּים וְיִשְׂרְאֵלִים וַחֲלָלִים מֻתָּרִים לָבוֹא זֶה בָּזֶה וְהַוָּלָד הוֹלֵךְ אַחַר הַזָּכָר). שֶׁנֶּאֱמַר (במדבר א יח) "וַיִּתְיַלְדוּ עַל מִשְׁפְּחֹתָם לְבֵית אֲבֹתָם". בֵּית אָבִיו הִיא מִשְׁפַּחְתּוֹ וְאֵין בֵּית אִמּוֹ מִשְׁפַּחְתּוֹ:
כסף משנה
15.
Priests, Levites, and Israelites are permitted to marry among each other.37E.g., there is no restriction against a priest marrying the daughter of a Levite or an Israelite. The status of the child is determined by that of the father.38Thus in the instance mentioned in the previous note, the offspring would be considered as priests. [Similarly,] Levites, Israelites, and challalim are permitted to marry among each other and the status of the child is determined by that of the father. [This is derived from Numbers 1:18]: "And they established the lineage of their families, according to their father's household." [Implied is that] the household of one's father is one's family and not the household of one's mother.

הלכה טז
לְוִיִּים וְיִשְׂרְאֵלִים וַחֲלָלִים גֵּרִים וַעֲבָדִים מְשֻׁחְרָרִים מֻתָּרִים לָבוֹא זֶה בָּזֶה. וְהַגֵּר וְהַמְשֻׁחְרָר שֶׁנָּשָׂא לְוִיָּה אוֹ יִשְׂרְאֵלִית אוֹ חֲלָלָה הֲרֵי הַבֵּן יִשְׂרְאֵלִי. וְיִשְׂרְאֵלִי אוֹ לֵוִי אוֹ חָלָל שֶׁנָּשְׂאוּ גִּיֹּרֶת אוֹ מְשֻׁחְרֶרֶת הַוָּלָד הוֹלֵךְ אַחַר הַזָּכָר:
כסף משנה
16.
Levites, Israelites, challalim, converts, and freed servants are permitted to marry among each other. When a convert or a freed servant marries the daughter of a Levite, the daughter of an Israelite, or a challalah, the offspring is an Israelite.39I.e., neither a Levite or a challal. When an Israelite, a Levite, or a challal marry a female convert or a freed maid-servant, the status of the child is determined by that of the father.40Thus the offspring of a Levite are Levites and the offspring of challalim are challalim.

הלכה יז
כָּל מִשְׁפָּחוֹת בְּחֶזְקַת כְּשֵׁרוֹת וּמֻתָּר לִשָּׂא מֵהֶן לְכַתְּחִלָּה. וְאַף עַל פִּי כֵן אִם רָאִיתָ שְׁתֵּי מִשְׁפָּחוֹת שֶׁמִּתְגָּרוֹת זוֹ בָּזוֹ תָּמִיד אוֹ רָאִיתָ מִשְׁפָּחָה שֶׁהִיא בַּעֲלַת מַצָּה וּמְרִיבָה תָּמִיד. אוֹ רָאִיתָ אִישׁ שֶׁהוּא מַרְבֶּה מְרִיבָה עִם הַכּל וְעַז פָּנִים בְּיוֹתֵר. חוֹשְׁשִׁין לָהֶן וְרָאוּי לְהִתְרַחֵק מֵהֶן שֶׁאֵלּוּ סִימָנֵי פַּסְלוּת הֵם. וְכֵן הַפּוֹסֵל אֶת אֲחֵרִים תָּמִיד. כְּגוֹן שֶׁנּוֹתֵן שֶׁמֶץ בְּמִשְׁפָּחוֹת אוֹ בִּיחִידִים וְאוֹמֵר עֲלֵיהֶן שֶׁהֵן מַמְזֵרִים. חוֹשְׁשִׁין לוֹ שֶׁמָּא מַמְזֵר הוּא. וְאִם אָמַר לָהֶן שֶׁהֵם עֲבָדִים חוֹשְׁשִׁין לוֹ שֶׁמָּא עֶבֶד הוּא. שֶׁכָּל הַפּוֹסֵל בְּמוּמוֹ פּוֹסֵל. וְכֵן כָּל מִי שֶׁיֵּשׁ בּוֹ עַזּוּת פָּנִים אוֹ אַכְזָרִיּוּת וְשׂוֹנֵא אֶת הַבְּרִיּוֹת וְאֵינוֹ גּוֹמֵל לָהֶם חֶסֶד חוֹשְׁשִׁין לוֹ בְּיוֹתֵר שֶׁמָּא גִּבְעוֹנִי הוּא. שֶׁסִּימָנֵי יִשְׂרָאֵל הָאֻמָּה הַקְּדוֹשָׁה בַּיְשָׁנִין רַחֲמָנִים וְגוֹמְלֵי חֲסָדִים. וּבַגִּבְעוֹנִים הוּא אוֹמֵר (שמואל ב כא ב) "וְהַגִּבְעֹנִים לֹא מִבְּנֵי יִשְׂרָאֵל הֵמָּה" לְפִי שֶׁהֵעֵזּוּ פְּנֵיהֶם וְלֹא נִתְפַּיְּסוּ וְלֹא רִחֲמוּ עַל בְּנֵי שָׁאוּל וְלֹא גָּמְלוּ לְיִשְׂרָאֵל חֶסֶד לִמְחל לִבְנֵי מַלְכָּם וְהֵם עָשׂוּ עִמָּהֶם חֶסֶד וְהֶחֱיוּם בַּתְּחִלָּה:
כסף משנה
17.
We operate under the presumption that all families are of acceptable lineage and it is permitted to marry their descendants as an initial and preferred option.41The Rambam is stating that it is not necessary to investigate thoroughly the lineage of a family before marrying into them. If it is a common presumption that a family is of acceptable lineage, one may marry a family member at the outset. When we know nothing of the lineage of the family, there are some authorities [Remo as quoted by the Tur (Even HaEzer 2)] who maintain that we do question his lineage and require proof that he is acceptable. Others (Rabbenu Asher and Rabbenu Nissim) differ and maintain that even if we do not know anything about a family's lineage, we assume that they are acceptable. See the discussion of the issue by Beit Shmuel 2:3.
The debate concerns the practice in the Talmudic age and in subsequent eras when Jewish observance was strong. At present, particularly in contemporary communities when there are many non-observant Jews and non-halachic divorce and similar problems are rampart, it is customary for Rabbinic courts to be careful and investigate the lineage of people before performing a marriage.
Nevertheless, if you see two families continuously quarreling with each other, you see one family that is always involved with strife and controversy, or you see a person who frequently quarrels with people at large and is very insolent, we suspect [their lineage]. It is fitting to distance oneself from such people for these are disqualifying characteristics.
Similarly, a person who always slurs the lineage of others, casting aspersions on the ancestry of families or individuals, claiming that they are mamzerim, we are suspicious that he himself is a mamzer. Similarly, if he calls others servants, we suspect that he is a servant. For whoever denigrates others, denigrates them with a blemish that he himself possesses.
Similarly, whenever a person is characterized by insolence and cruelty, hating people and not showing kindness to them, we seriously suspect that he is a Gibeonite. For the distinguishing signs of the holy nation of Israel is that they are meek, merciful, and kind. With regard to the Gibeonites, [II Samuel 21:2] states: "The Gibeonites are not of the Jewish people." For they acted extremely brazenly and would not be appeased. They did not show mercy to the sons of [King] Saul, nor did they show kindness to the Jews to forgive the descendants of their king,42As mentioned in the notes to Chapter 12, Halachah 23, as related in II Samuel, ch. 21, there was a famine for three years in Eretz Yisrael. Through prophetic vision, David learned that the reason for the famine was Saul's oppression of the Gibeonites (exactly what Saul did to oppress them is a matter of discussion among the Rabbis). David asked the Gibeonites what they desired to be appeased for this oppression. They answered that they wanted to slay seven of his descendants. David handed over seven of Saul's descendants to them and they hung them and left their corpses on the gallows. For this act of cruelty, David decreed that they should never marry among the Jewish people. while [the Jews] had shown them kindness and allowed them to live.43Joshua, Chapter 9, relates that after the Jews' conquest of Jericho and Ai, the inhabitants of Gibeon:

Acted cunningly... They took old sacks upon their donkeys, old and rent wine bottles... old, worn and patched shoes... and came to Joshua at Gilgal. They told him:... "We have come from a distant country. Therefore, make a covenant with us." Joshua made a covenant with them... and the princes of the congregation swore to them.

After the ruse was discovered, Joshua and the people honored the covenant and allowed the Gibeonites to live. Moreover, they even came to their defense when they were attacked by other Canaanite nations.

הלכה יח
מִשְׁפָּחָה שֶׁקָּרָא עָלֶיהָ עַרְעַר וְהוּא שֶׁיָּעִידוּ שְׁנַיִם שֶׁנִּתְעָרֵב בָּהֶן מַמְזֵר אוֹ חָלָל אוֹ שֶׁיֵּשׁ בָּהֶן עַבְדוּת הֲרֵי זֶה סָפֵק. וְאִם מִשְׁפַּחַת כֹּהֲנִים הִיא לֹא יִשָּׂא מִמֶּנָּה אִשָּׁה עַד שֶׁיִּבְדֹּק עָלֶיהָ אַרְבַּע אִמָּהוֹת שֶׁהֵן שְׁמוֹנֶה. אִמָּהּ. וְאֵם אִמָּהּ. וְאֵם אֲבִי אִמָּהּ. וְאֵם אֵם אֲבִי אִמָּהּ. וְכֵן הוּא בּוֹדֵק עַל אֵם אָבִיהָ. וְאֵם אֵם אָבִיהָ. וְאֵם אֲבִי אָבִיהָ. וְאֵם אֵם אֲבִי אָבִיהָ:
כסף משנה
18.
When [the purity of] a family's [lineage] has been disputed, i.e., two individuals testify44The Beit Shmuel 2:6 cites the opinion of Rashi (Kiddushin 76a) which maintains that even if the two people cast aspersions on the family's lineage without delivering formal testimony, such investigations must be made. that a mamzer or a challal has intermingled with that family or there are servants among them,45We are not concerned that a servant intermingled among them, for even if a servant did conceive a child with a woman from a priestly family, the child is acceptable. Our suspicion is that one of the priests had relations with a maid-servant and she bore him a son or daughter who was raised as a member of the priest's family (Chelkat Mechokek 2:2). the matter is questionable. If the family are priests, one should not marry a woman from them until he46See Halachah 21and notes which discuss whether a woman is required to make such an investigation or not. investigates the lineage of four - actually eight47I.e., the obligation is to check the lineage of four women: her mother, the mother of her maternal grandfather, her paternal grandmother, and the paternal grandmother of her paternal grandfather. Nevertheless, to verify the acceptability of the lineage of these women, it is necessary to verify that their mothers are also of acceptable lineage, thus reaching a total of eight (Rabbenu Nissim).- of her maternal ancestors: her mother, her maternal grandmother, the mother of her maternal grandfather, the maternal grandmother of her maternal grandfather. Similarly, he must investigate the lineage of her paternal grandmother, the mother of her paternal grandmother, the mother of her paternal grandfather, and the mother of the mother of her paternal grandfather.

הלכה יט
וְאִם הָיְתָה מִשְׁפָּחָה זוֹ שֶׁקָּרָא עָלֶיהָ עַרְעַר לְוִיִּם אוֹ יִשְׂרְאֵלִים. מוֹסִיף לִבְדֹּק לָהֶם זוּג אֶחָד. וְנִמְצָא בּוֹדֵק עֶשֶׂר אִמָּהוֹת. שֶׁהָעֵרוּב בַּלְוִיִּם וְיִשְׂרְאֵלִים יֶתֶר מִן הַכֹּהֲנִים:
כסף משנה
19.
If the family whose lineage was disputed were Levites or Israelites, it is necessary to check [the lineage of] another pair of women. Thus one must check ten maternal ancestors.48I.e., one must add the mother of her maternal grandmother and the maternal grandmother of her paternal grandmother (Merkevet HaMishneh).
The Maggid Mishneh questions the Rambam's statements, noting that from Kiddushin 76a, it would appear that one would have to check the lineage of twelve or sixteen women.
[The rationale is that unacceptable people] intermarry among Levites and Israelites more frequently than among priests.

הלכה כ
וְלָמָּה בּוֹדֵק בַּנָּשִׁים בִּלְבַד. מִפְּנֵי שֶׁהָאֲנָשִׁים כָּל עֵת שֶׁיָּרִיבוּ זֶה עִם זֶה יְחָרֵף אֶת חֲבֵרוֹ בִּפְסוּל שֶׁיֵּשׁ בְּיִחוּסוֹ. וְאִלּוּ הָיָה שָׁם פָּסוּל הָיָה נִשְׁמָע. אֲבָל הַנָּשִׁים אֵין מְחָרְפוֹת בְּיוּחֲסִין:
כסף משנה
20.
Why is it necessary to check the lineage only of the woman's maternal [ancestors]? Because whenever men argue with each other, one will malign the other with a blemish that exists in his lineage. Thus if he was unacceptable, the matter would have been made known.49I.e., after the blemish was mentioned in quarrels, it would become a matter of public knowledge and investigated accordingly. Women, by contrast, do not malign [each other] with regard to blemishes in their lineage.50Hence, their blemished lineage would not be public knowledge.

הלכה כא
וְלָמָּה יִבְדֹּק הָאִישׁ כְּשֶׁיִּרְצֶה לִשָּׂא מִמִּשְׁפָּחָה זוֹ שֶׁהֻרְעָה חֶזְקָתָהּ וְלֹא תִּבְדֹּק אִשָּׁה שֶׁתִּנָּשֵׂא לָהֶן. מִפְּנֵי שֶׁלֹּא הֻזְהֲרוּ כְּשֵׁרוֹת לְהִנָּשֵׂא לִפְסוּלִין:
כסף משנה
21.
Why must a man make an investigation when he desires to marry a woman from a family concerning whom the presumption of acceptable lineage has been impaired and yet a woman who desires to marry into this family is not required to make an investigation? Because woman of acceptable lineage were not warned against marrying [men of] unacceptable lineage.51The Rambam's statements (based on his interpretation of Kiddushin 76b) have attracted the attention of the commentaries who raise a basic question: The prohibition against marrying an unacceptable partner (e.g., a mamzer) applies equally to men and women (see Chapter 1, Halachah 1). Why then is a woman not warned with regard to this matter?
The Maggid Mishneh (quoting Rashi's commentary to Kiddushin 76a) states that here, the Rambam intent is that since the Torah did not forbid a woman of the priestly family from marrying a challal, our Sages did not require a woman to make an investigation even when there is a question whether her future husband is entirely unacceptable.
According to Rashi who interprets "disputing a family's lineage" (Halachah 18) as merely casting aspersions, this interpretation is tenable. After all, we have no hard and fast evidence that the man's lineage is unacceptable. But according to the Rambam, who defines that term as referring to testimony delivered in court, the original question remains. Since there is a firm possibility that a Scriptural prohibition is involved, why shouldn't a woman be required to make an investigation? Among the resolutions offered is that of the Chelkat Mechokek 2:5 is that the Rambam would require an investigation even when a woman desires to marry. Nevertheless, the investigation need not include all of the eight (or ten) women mentioned by the Rambam. Such thoroughness is required only when a man seeks to marry.
See the gloss of the Maggid Mishneh to Halachah 18 and the Chelkat Mechokek 2:3 which cite differing opinions which also require a woman to make a full-fledged investigation of the lineage of a man she desires to marry if there are questions concerning his lineage.

הלכה כב
כָּל שֶׁקּוֹרִין לוֹ מַמְזֵר וְשׁוֹתֵק. אוֹ נָתִין וְשׁוֹתֵק. אוֹ חָלָל וְשׁוֹתֵק. אוֹ עֶבֶד וְשׁוֹתֵק. חוֹשְׁשִׁין לוֹ וּלְמִשְׁפַּחְתּוֹ וְאֵין נוֹשְׂאִין מֵהֶן אֶלָּא אִם כֵּן בּוֹדְקִין כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
22.
Whenever a person is called a mamzer, a netin a challal, or a servant and he remains silent, we suspect [the lineage of] him and his family52We assume that he would not remain silent when his lineage is slurred unless there was some truth to the assertions.
The Ra'avad states that the Rambam's statement (taken from Ketubot 14b) held true only in the Talmudic era when a person who insulted a colleague's lineage was placed under a ban of ostracism. Hence when a person remained silent instead of appealing to the court, we could assume that he was admitting to the accuser's assertion. In the present era, by contrast, there is no punishment given for making such slurs. Hence, the insulted person would have no benefit in bringing the matter to the court's attention. Accordingly, it is preferable to remain silent.
The Ramban and the Rashba explain that the Rambam's words apply with regard to a family concerning which there already exist doubts with regard to their lineage. When, by contrast, their lineage is considered unblemished, it is preferable for them to remain silent. Rabbenu Nissim states that the insulted person's silence is considered significant only when it is common for him to protest other matters. If, however, he usually remains silent, the fact that he does so in this situation as well is of no consequence. The Shulchan Aruch (Even HaEzer 2:4) quotes the Rambam's words and the Rama quotes the latter views.
and do not marry women from this [family] unless an investigation was made as we explained.53As explained in Halachot 18-19. The investigation is sufficient to clarify any difficulties, for the suspicion created by his silence is not a more serious factor than the testimony of the witnesses mentioned in Halachah 18 (Maggid Mishneh).

הלכה כג
מִשְׁפָּחָה שֶׁנִּתְעָרֵב בָּהּ סְפֵק חָלָל כָּל אַלְמָנָה מֵאוֹתָהּ מִשְׁפָּחָה אֲסוּרָה לְכֹהֵן לְכַתְּחִלָּה. וְאִם נִשֵּׂאת לֹא תֵּצֵא מִפְּנֵי שֶׁהֵן שְׁתֵּי סְפֵקוֹת. שֶׁמָּא זוֹ אַלְמְנַת אוֹתוֹ חָלָל שֶׁמָּא אֵינָהּ אַלְמְנָתוֹ. וְאִם נֹאמַר שֶׁהִיא אַלְמְנָתוֹ שֶׁמָּא חָלָל הוּא שֶׁמָּא אֵינוֹ חָלָל. אֲבָל אִם נִתְעָרֵב בָּהּ חָלָל וַדַּאי כָּל אִשָּׁה מֵהֶן אֲסוּרָה לְכֹהֵן עַד שֶׁיִּבְדֹּק. וְאִם נִשֵּׂאת תֵּצֵא. וְהוּא הַדִּין אִם נִתְעָרֵב בָּהּ סְפֵק מַמְזֵר אוֹ מַמְזֵר וַדַּאי. שֶׁאֵשֶׁת מַמְזֵר וְאֵשֶׁת חָלָל לִכְהֻנָּה אִסּוּר אֶחָד הוּא כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
23.
When there is a suspicion that a person concerning whom there is a question whether he is a challal married into a family,54I.e., there is a report that a man of questionable status married into a family, but the identity of that man and that of his wife are not known. every widow from that family is forbidden to a priest at the outset.55One might think that because of the multiple doubt involved the woman would be permitted at the outset. Nevertheless, because of the stringency of the laws of proper lineage, this leniency is not taken. [After the fact,] if she married [a priest], she need not be divorced because there are two questions involved: Maybe this is the widow of that challal56And as is stated in Chapter 18, Halachah 1, a woman who engaged in relations with a challal is forbidden to the priesthood. or maybe it is not? Even if you say that she was his widow, maybe he was a challal or maybe he was not?57Since there is a multiple doubt (sefek sefeikah), the woman is permitted.
If, however, a person who was definitely a challal married into a family, every woman58I.e., both widows and daughters (Kessef Mishneh). from that family is forbidden to a priest until he conducts an investigation. If he marries [such a woman without an investigation], she must be divorced. The same laws59I.e., the first clause applies to a person's whose status as a mamzer is a matter of question and the second clause to whose unacceptable status is definite (Kessef Mishneh).
In his Kessef Mishneh, Rav Yosef Caro mentions opinions that rule more stringently and forbid marriage even when there is a report that a person about whom a question was raised whether or not he is a mamzer married into a family. In his Shulchan Aruch (Even HaEzer 2:5), however, he quotes the Rambam's view.
apply if a person regarding whom there is a question whether he is a mamzer or a person who is definitely mamzer became intermingled in the family. For the same prohibition applies to the priesthood with regard to the wife of a challal and the wife of a mamzer, as we explained.60Chapter 18, Halachah 1.

קדושה הלכות איסורי ביאה פרק יט
Kedushah Issurei Biah Chapter 19