Halacha

הלכה א
עוֹשֶׂה אָדָם שָׁלִיחַ לְהַפְרִישׁ לוֹ תְּרוּמוֹת וּמַעַשְׂרוֹת שֶׁנֶּאֱמַר (במדבר יח כח) "כֵּן תָּרִימוּ גַם אַתֶּם" לְרַבּוֹת שְׁלוּחֲכֶם. וְאֵין עוֹשִׂין שָׁלִיחַ עַכּוּ''ם שֶׁנֶּאֱמַר גַם אַתֶּם מָה אַתֶּם בְּנֵי בְּרִית אַף שְׁלוּחֲכֶם בְּנֵי בְּרִית:
כסף משנה
1.
A person may appoint an agent to separate terumah and the tithes for him, as [Numbers 18:28] states: "So shall you separate, also you." [The wording implies] the inclusion of an agent.1By saying "also you," the verse implies that there is someone other than you - an agent - that may also separate terumah [the Rambam's Commentary to the Mishnah (Terumah 1:1)]. A gentile may not be appointed as an agent, because [the phrase] "also you" [implies an equation between you and your agent]. Just as you are a member of the covenant, your agent must be a member of the covenant.2This is a general principle applying not only with regard to terumah. A gentile cannot serve as an agent for a Jew in any matter (Kiddushin 41b).

הלכה ב
חֲמִשָּׁה לֹא יִתְרֹמוּ וְאִם תָּרְמוּ אֵין תְּרוּמָתָן תְּרוּמָה. הַחֵרֵשׁ. וְהַשּׁוֹטֶה. וְהַקָּטָן. וְהָעַכּוּ''ם שֶׁתָּרַם אֶת שֶׁל יִשְׂרָאֵל וַאֲפִלּוּ בִּרְשׁוּתוֹ. וְהַתּוֹרֵם אֶת שֶׁאֵינוֹ שֶׁלּוֹ שֶׁלֹּא בִּרְשׁוּת הַבְּעָלִים. אֲבָל הַתּוֹרֵם מִשֶּׁלּוֹ עַל שֶׁל אֲחֵרִים הֲרֵי זוֹ תְּרוּמָה וְתִקֵּן פֵּרוֹתֵיהֶם. וְטוֹבַת הֲנָאָה שֶׁלּוֹ שֶׁנּוֹתְנָהּ לְכָל כֹּהֵן שֶׁיִּרְצֶה:
כסף משנה
2.
There are five [types of individuals] who should not separate terumah and [even] if they do, [the produce] they separated is not considered as terumah: A deaf-mute,3As the Rambam explains in his Commentary to the Mishnah (Terumah 1:2) although the term cheresh refers to someone who cannot hear, in a halachic context, the intent is someone who also cannot speak. He is referred to as a cheresh because it is his inability to hear that prevents him from learning how to speak. a mentally or emotionally unstable person, a minor,4These three individuals are considered as incapable of controlling their affairs. Hence they are not obligated in the observance of the Torah and its mitzvot. Just as they are not responsible for themselves, they cannot discharge the responsibilities of others. a gentile who separated terumah from produce belonging to a Jew, even with his permission,5For as stated above, a gentile cannot act as an agent for a Jew. and a person who separates terumah from produce that does not belong to him without the owner's permission.6If he is granted the owner's permission, he is considered as his agent and the separation is effective as stated above. If, however, a person separates terumah from his own produce for the produce of others, the produce is terumah and [the colleague's] produce has been prepared for use. The satisfaction [of allocating the terumah] belongs [to the person who separated it and he may] give to whichever priest he desires.

הלכה ג
הַתּוֹרֵם שֶׁלֹּא בִּרְשׁוּת אוֹ שֶׁיָּרַד לְתוֹךְ שְׂדֵה חֲבֵרוֹ וְלִקֵּט פֵּרוֹת שֶׁלֹּא בִּרְשׁוּת כְּדֵי שֶׁיִּקָּחֵם וְתָרַם. אִם בָּא בַּעַל הַבַּיִת וְאָמַר לוֹ כַּלֵּךְ אֵצֶל יָפוֹת. אִם הָיוּ שָׁם יָפוֹת מִמַּה שֶּׁתָּרַם תְּרוּמָתוֹ תְּרוּמָה שֶׁהֲרֵי אֵינוֹ מַקְפִּיד. וְאִם לֹא הָיוּ שָׁם יָפוֹת אֵין תְּרוּמָתוֹ תְּרוּמָה שֶׁלֹּא אָמַר לוֹ אֶלָּא עַל דֶּרֶךְ מִחוּי. וְאִם בָּא בַּעַל הַבַּיִת וְלִקֵּט וְהוֹסִיף בֵּין יֵשׁ לוֹ יָפוֹת מֵהֶן בֵּין אֵין לוֹ תְּרוּמָתוֹ תְּרוּמָה:
כסף משנה
3.
[The following rules apply when a person] separates terumah [from a colleague's produce] without permission or descends into his colleague's field and gathered produce without permission so that he could take them [for himself], but separate some as terumah. When the owner comes and says: "You should have taken better ones,"7Our translation is based on Rashi's commentary (Bava Metzia 22a). if there are better ones than those separated as terumah, the separation is effective,8According to this approach, the statement "You should have taken better ones" is understood simply. The owner in truth desired that the person give the priest the best produce possible as terumah. because [the owner] did not object.9Thus we consider it as if the person acted with the owner's consent and thus functioned as his agent. Since a mitzvah is involved and ultimately, he consented, we assume that this was his intent from the outset (Radbaz, Kessef Mishneh). Also, implied is that the owner was willing to allow the person to take a certain amount of the produce as his own. Note the Turei Zahav 331:15 who maintains that the Rambam's ruling runs contrary to the simple meaning of the passage in Bava Metzia, loc. cit., and rejects the resolutions offered by the Kessef Mishneh. Note, also, the contrast to Hilchot Ishut 5:8. If there are not better ones, his separation is not effective, for his statements were made as an objection.10I.e., we assume that he was speaking facetiously. If the owner came and gathered produce and added it to the quantity separated,11We interpret that as an expression of consent to the other person's actions. whether he possesses better produce or not, his separation is effective.

הלכה ד
חֲמִשָּׁה לֹא יִתְרֹמוּ וְאִם תָּרְמוּ תְּרוּמָתָן תְּרוּמָה. חֵרֵשׁ מְדַבֵּר וְאֵינוֹ שׁוֹמֵעַ מִפְּנֵי שֶׁאֵינוֹ שׁוֹמֵעַ הַבְּרָכָה. וְהָאִלֵּם שֶׁשּׁוֹמֵעַ וְאֵינוֹ מְדַבֵּר. וְהֶעָרוּם. מִפְּנֵי שֶׁאֵינָן יְכוֹלִין לְבָרֵךְ. וְהַשִּׁכּוֹר וְהַסּוּמָא מִפְּנֵי שֶׁאֵינָן יְכוֹלִין לְכַוֵּן וּלְהַפְרִישׁ אֶת הַיָּפֶה:
כסף משנה
4.
There are five12Terumah 1:4 also mentions a person who had a seminal emission. He is prohibited, because he is not allowed to recite a blessing until he immerses himself in a mikveh. The Rambam does not mention such a person here, because - as stated in Hilchot K'riat Shema 4:8; Hilchot Tefilah 4:4-6 - Ezra's decree restricting a person who had a seminal emission from prayer and Torah study was never fully accepted and ultimately, nullified by the Rabbis. In the present age, such a person should recite blessings even though he has not yet immersed. who should not separate terumah, but if they do, their separation is effective:
a person who is deaf, but not mute, because he cannot hear the blessing,13This category is not mentioned in the mishnah, loc. cit. The Rambam mentions it, based on the principle (see Hilchot Berachot 1:7) that a person who recites a blessing should recite it in a manner that enables him to hear it. a mute who can hear, but not speak and a person who is naked, because they cannot recite the blessing,14A person who cannot speak is physically incapable of reciting the blessing. A person who is naked is forbidden to recite the blessing, because his personal state is not considered as appropriate for the recitation of a blessing (see Shabbat 23b). and a person who is drunk15This is speaking about a person who is slightly intoxicated, but still able to function. If a person is intoxicated to the extent that is not at all in command of his mental faculties, he is considered as one who is intellectually incapable and his separation is of no consequence whatsoever. See Hilchot Mechirah 29:18. and a blind person, because they cannot make distinctions and separate the most attractive portion [as terumah].16And as an initial and preferable measure, the finest portion of the produce should be separated as terumah (see Chapter 5, Halachah 1). When quoting this law, the Shulchan Aruch (Yoreh De'ah 331:32) states that in the present age, when the terumah is ultimately destroyed, we are not precise in separating the finest portion of the crops as terumah. Hence, it is also acceptable if individuals in the latter two categories also separate terumah.

הלכה ה
קָטָן שֶׁהִגִּיעַ לְעוֹנַת נְדָרִים אַף עַל פִּי שֶׁלֹּא הֵבִיא שְׁתֵּי שְׂעָרוֹת וְלֹא נַעֲשָׂה גָּדוֹל אִם תָּרַם תְּרוּמָתוֹ תְּרוּמָה. וַאֲפִלּוּ בִּתְרוּמָה שֶׁל תּוֹרָה הוֹאִיל וְנִדְרֵיהֶן וְהֶקְדֵּשָׁן קַיָּמִין מִן הַתּוֹרָה כְּמוֹ שֶׁבֵּאַרְנוּ בִּנְדָרִים:
כסף משנה
5.
When a minor reaches the age when his vows may be of consequence17I.e., a male minor who is twelve years old and a female minor who is eleven years old, provided they know the significance of vows, or a male of thirteen and a female of twelve who have not manifested signs of physical maturity, . - even though he has not manifested signs of physical maturity and he has not attained majority - separates terumah, his separation is of consequence.18In one of his responsa, however, the Rambam writes that as an initial preference, it is not desirable for a minor to separate terumah until he manifests signs of physical maturity. [This applies] even with regard to terumah mandated by Scriptural Law. [The rationale is that] their vows and their consecration [of property] is valid according to Scriptural Law, as explained in [Hilchot] Nedarim.19Hilchot Nedarim 11:1-5.

הלכה ו
הָאוֹמֵר לִשְׁלוּחוֹ צֵא וּתְרֹם לִי וְהָלַךְ לִתְרֹם וְאֵינוֹ יוֹדֵעַ אִם תָּרַם וְאִם לֹא תָּרַם וּבָא וּמָצָא כְּרִי תָּרוּם אֵין חֶזְקָתוֹ תָּרוּם. שֶׁאֵין אוֹמְרִין בְּאִסּוּרִין חֶזְקַת שָׁלִיחַ עוֹשֶׂה שְׁלִיחוּתוֹ לְהָקֵל אֶלָּא לְהַחֲמִיר וְחוֹשֵׁשׁ שֶׁמָּא אַחֵר תָּרַם שֶׁלֹּא בִּרְשׁוּת:
כסף משנה
6.
When a person tells his agent: "Go and separate terumah for me" and he goes to separate terumah, but [the principal] does not know whether he [actually] separated terumah or not, [even] when he discovers that terumah was separated from the granary, we do not assume that [he] separated terumah. For with regard to prohibitions, we apply the principle:20Eruvin 31b; Gittin 64a,b et al. "An agent can be assumed to have carried out his mission," only when that leads to a stringency, not when it leads to a leniency.21I.e., we are uncertain whether we can rely on the fact that an agent will carry out his mission. Hence, if his doing so would lead to a prohibition, we rule stringently and assume that he carried out his mission (see Hilchot Ishut 9:6). If, however, his doing so would lead to a leniency, we do not make such an assumption.
The Shulchan Aruch (Yoreh De'ah 331:34) quotes the Rambam's ruling. The Tur and the Rama, however, rule that in such a situation, we can assume that the agent carried out his mission, for failing to do so would create a spiritual stumbling block for the principal.
[Instead,] we suspect that another person separated the terumah without his permission.22In which instance, the separation of terumah would not be effective, as stated in Halachah 2.

הלכה ז
הָאוֹמֵר לִשְׁלוּחוֹ צֵא וּתְרֹם תּוֹרֵם כְּדַעְתּוֹ שֶׁל בַּעַל הַבַּיִת. אִם הָיָה יוֹדֵעַ בּוֹ שֶׁהוּא בַּעַל עַיִן רָעָה מַפְרִישׁ אֶחָד מִשִּׁשִּׁים. וְאִם הָיָה בַּעַל נֶפֶשׁ שְׂבֵעָה מַפְרִישׁ אֶחָד מֵאַרְבָּעִים. וְאִם אֵינוֹ יוֹדֵעַ דַּעְתּוֹ מַפְרִישׁ לוֹ בֵּינוֹנִית אֶחָד מֵחֲמִשִּׁים. נִתְכַּוֵּן לְבֵינוֹנִית וְעָלְתָה בְּיָדוֹ אֶחָד מֵאַרְבָּעִים אוֹ אֶחָד מִשִּׁשִּׁים תְּרוּמָתוֹ תְּרוּמָה. וְאִם נִתְכַּוֵּן לְהוֹסִיף עַל הַבֵּינוֹנִית וְתָרַם אֲפִלּוּ אֶחָד מִתִּשְׁעִים וְתִשְׁעָה אֵין תְּרוּמָתוֹ תְּרוּמָה:
כסף משנה
7.
When a person tells his agent: "Go and separate terumah," he should separate according to the temperament of the owner. If he knows that he is parsimonious, he should separate one sixtieth. If he was generous, he should separate one fortieth. If he does not know his temperament, he should make the average separation, one fiftieth. If he intended to make the average separation, but it turned out that he separated one fortieth or one sixtieth, his separation is effective.23In his Commentary to the Mishnah (Terumot 4:4), the Rambam writes that if the agent gave more or less than the average measure unintentionally, his separation is effective. In contrast to the situation described in Chapter 5, Halachah 5, here the agent is acting with the principal's permission. Hence, even if he deviated from the amount he could be expected to give, his act is of consequence. If he intended to add to the average separation, and he separated even one forty-ninth,24Our translation is based on authoritative manuscripts and early printings of the Mishneh Torah. The standard published text has a slightly different version. his separation is not effective.25The Radbaz interprets this as meaning that the agent knew the amount the principal would prefer giving and intentionally gave more. Since he intentionally set aside a measure that differs from the principal's wishes, he is considered as acting without permission.

הלכה ח
פֵּרוֹת הַשֻּׁתָּפִין חַיָּבוֹת בִּתְרוּמָה וּמַעַשְׂרוֹת שֶׁנֶּאֱמַר (במדבר יח כח) "מַעְשְׂרֹתֵיכֶם" אֲפִלּוּ שֶׁל שְׁנַיִם. וְהַשֻּׁתָּפִין אֵינָן צְרִיכִין לִטּל רְשׁוּת זֶה מִזֶּה. אֶלָּא כָּל הַתּוֹרֵם מֵהֶן תְּרוּמָתוֹ תְּרוּמָה. תָּרַם אֶחָד מֵהֶן וּבָא הַשֵּׁנִי וְתָרַם תְּרוּמָה שְׁנִיָּה שֶׁהֲרֵי לֹא יָדַע שֶׁחֲבֵרוֹ תָּרַם. אִם הָיוּ מְמַחִין זֶה עַל זֶה תְּרוּמַת הַשֵּׁנִי אֵינָהּ תְּרוּמָה. וְאִם לֹא הָיוּ מְמַחִין וְתָרַם הָרִאשׁוֹן כַּשִּׁעוּר (אֵין תְּרוּמַת הַשֵּׁנִי תְּרוּמָה לֹא תָּרַם הָרִאשׁוֹן כַּשִּׁעוּר) תְּרוּמַת שְׁנֵיהֶן תְּרוּמָה:
כסף משנה
8.
There is an obligation to separate terumah and tithes from produce belonging to partners, for [Numbers 18:28] speaks of "your tithes," [using a plural term,] implying even from two people.
Partners do not have to receive permission from each other. Instead, whenever anyone separates terumah, the separation is effective. [The following rules apply when] one of them separated terumah and then the other came and separated terumah, because he did not know that his colleague had separated it. If they relied26Our translation is based on the glosses of the Radbaz and the Kessef Mishneh. Other definitions have been offered in different sources. on each other, the terumah separated by the second is not of consequence.27Because the mitzvah was completed by the terumah separated by the first. Had the second known that the first had made the separation, he would not have separated terumah. Thus the separation of the second was made in error. If they did not rely on each other, but the first one separated an appropriate amount, the separation of the second one is of no consequence.28Had the second known that the first separated the appropriate amount, he would not have separated the terumah. Hence, here also, we say that the separation of the second was made in error. If the first did not separate the appropriate amount, the separation of the second one is also of consequence.29And it completes the requirement made by our Sages (Kessef Mishneh).
When quoting this law, the Shulchan Aruch (Yoreh De'ah 331:35) emphasizes that in the present age, when it is sufficient to separate even the slightest amount as terumah, the first person's separation is always sufficient and the second's separation is never of consequence.

הלכה ט
הָאוֹמֵר לְשֻׁתָּפוֹ אוֹ לְבֶן בֵּיתוֹ אוֹ לְעַבְדּוֹ אוֹ לְשִׁפְחָתוֹ לִתְרֹם. וְהָלְכוּ לִתְרֹם וּבִטֵּל שְׁלִיחוּתוֹ קֹדֶם שֶׁיִּתְרֹמוּ. אִם לֹא שִׁנָּה הַשָּׁלִיחַ תְּרוּמָתוֹ תְּרוּמָה. וְאִם שִׁנָּה כְּגוֹן שֶׁאָמַר לוֹ תְּרֹם מִן הַצָּפוֹן וְתָרַם מִן הַדָּרוֹם הוֹאִיל וּבִטֵּל שְׁלִיחוּתוֹ מִקֹּדֶם אֵינָהּ תְּרוּמָה:
כסף משנה
9.
[The following rules apply when a person] tells his agent, his attendant,30Our translation is based on the Rambam's Commentary to the Mishnah (Terumot 3:4). his servant, or his maid-servant to separate terumah and they went to separate the terumah, but he nullified their agency before they made the separation. If the agent did not deviate [from the principal's instructions], his separation is effective.31Even though the principal nullified the agency. In his Commentary to the Mishnah (loc. cit), the Rambam explains the rationale for his ruling. The nullification of the agency was brought about through speech and speech does not have the power to effect such a change.
The Ra'avad and the Tur question the Rambam's decision, for seemingly, just as the appointment of the agent was made through speech, the nullification of his agency can also be made through speech. The Radbaz and the Kessef Mishneh note that in fact, the Rambam himself accepts this concept in Hilchot Ishut 9:20 with regard to appointing an agent to consecrate a woman as one's wife. Both of these commentaries quote possible rationales to distinguish between the separation of terumah and the consecration of a woman.
The Shulchan Aruch (Yoreh De'ah 331:36) quotes the Rambam's ruling, while the Rama cites that of the Ra'avad and the Tur.
If he did deviate, e.g., the principal told him: "Separate from the northern side," and he separated from the southern side, since he nullified the agency previously, the separation is not effective.32Here too, the Tur questions the Rambam's wording. Seemingly, since the agent deviated from the principal's instructions, the agency is nullified even if the principal did not state that he was nullifying it. The Radbaz explains that a deviation as slight as the side of the produce from which terumah should be separated would not be sufficient to nullify the agency unless the principal had already expressed his willingness to do so.

הלכה י
אָרִיס שֶׁתָּרַם וּבָא בַּעַל הַבַּיִת וְעִכֵּב אִם עַד שֶׁלֹּא תָּרַם עִכֵּב אֵין תְּרוּמָתוֹ תְּרוּמָה וְאִם מִשֶּׁתָּרַם עִכֵּב תְּרוּמָתוֹ תְּרוּמָה. וְהָאַפּוֹטְרוֹפְּסִין תּוֹרְמִין מִנִּכְסֵי יְתוֹמִים:
כסף משנה
10.
[The following rules apply when] a sharecropper separates terumah and the owner [of the land] objects. If he objects before he completes the separation of the terumah, the separation is not of consequence.33The Radbaz notes that, in all instances, he is allowed to separate the tithes for his own portion of the crops. If he objected after the separation, the separation is of consequence.34The Siftei Cohen 331:67 states that his separation is effective, because we can assume that he appointed him as an agent.
Guardians may separate terumah from the property of orphans.35The Kessef Mishneh refers to the Rambam's ruling, Hilchot Nachalot 11:9: Guardians should separate terumah and the tithes from the [crops of] orphans so that they can provide them with food. For we may not feed orphans forbidden substances. They may not, however, tithe or separate terumah from produce so that it will be ready for use [by others]. Instead, they should sell it as tevel. Those who desire to make it ready for use will do so.

הלכה יא
הַגַּנָּב וְהַגַּזְלָן וְהָאַנָּס תְּרוּמָתָן תְּרוּמָה. וְאִם הָיוּ הַבְּעָלִים רוֹדְפִין אַחֲרֵיהֶן אֵין תְּרוּמָתָן תְּרוּמָה:
כסף משנה
11.
The separation of terumah by a thief, a robber, and a man of force36One who compelled a person to give him or sell him produce. is effective.37From a comparison to the following clause, we assume that this clause is speaking about a situation where the owners already despaired of receiving their produce again. Since the separation of terumah changed the status of the crops, the thief or robber acquires them because of the owner's desperation and their change of status. Since the thief is now the owner, his separation is effective. If the owner is pursuing them,38With the intent of retaking his produce. the separation is not effective.39Since the owner has not given up hope for the recovery of the produce, it has not left his possession. Thus the thief is not separating terumah from produce that belongs to him.

הלכה יב
הַבֵּן וְהַשָּׂכִיר וְהָעֶבֶד וְהָאִשָּׁה תּוֹרְמִין עַל מַה שֶּׁהֵן אוֹכְלִין. אֲבָל לֹא יִתְרְמוּ עַל הַכּל שֶׁאֵין אָדָם תּוֹרֵם דָּבָר שֶׁאֵינוֹ שֶׁלּוֹ. הַבֵּן כְּשֶׁאוֹכֵל עִם אָבִיו וְהָאִשָּׁה בְּעִסָּתָהּ תּוֹרְמִין מִפְּנֵי שֶׁהֵן בִּרְשׁוּת:
כסף משנה
12.
A child, a worker, a servant, and a wife should separate terumah for [produce] that they are eating, but not for the entire [crop].40Since this produce was given to them to eat, we assume that license was also given for them to separate terumah from it. For a person should not separate terumah from [produce] that does not belong to him.
When a son eats together with his father41Since he is eating together with his father - in contrast to the child mentioned in the previous halachah - we assume that his father gives him license to separate the terumah. and a woman [makes] dough,42Since she is given the responsibility of preparing the dough, she is also given the license to separate terumah from it. they may separate terumah, because they have license to do so.

הלכה יג
הַפּוֹעֲלִים אֵין לָהֶן רְשׁוּת לִתְרֹם שֶׁלֹּא מִדַּעַת בַּעַל הַבַּיִת. חוּץ מִן הַדּוֹרְכִין בְּגַת שֶׁאִם יִרְצוּ לְטַמֵּא אֶת הַיַּיִן הֲרֵי הֵן מְטַמְּאִים מִיָּד. וּלְפִי שֶׁמָּסַר לָהֶן וְהֶאֱמִינָן עַל כֵּן הֲרֵי הֵן כִּשְׁלוּחִין וְאִם תָּרְמוּ תְּרוּמָתָן תְּרוּמָה:
כסף משנה
13.
Workers do not have license to separate terumah without the consent of the owner with the exception of those who tread grapes in the vat. [They are given this license because] if they desired to make the wine impure, they could do so immediately. Since the wine was thus given over to their domain and they were entrusted with it, they are considered as agents. If they separate terumah, the separation is effective.43Since we are all impure in the present age, this law no longer applies and it is not cited by the Shulchan Aruch (Yoreh De'ah 331:42) together with the first part of the halachah.

הלכה יד
פּוֹעֵל שֶׁאָמַר לוֹ בַּעַל הַבַּיִת כְּנֹס לִי גָּרְנִי וּתְרֹם וְתָרַם וְאַחַר כָּךְ כָּנַס תְּרוּמָתוֹ תְּרוּמָה:
כסף משנה
14.
When a worker is told by the owner: "Bring my granary in and separate terumah," but he separates and then brings the granary in, his separation is effective.44Although he has deviated from the principal's words, we still consider him as an agent. The rationale is that the principal did not make an explicit statement that he was particular that the worker take these steps in this order. Indeed, the common practice is to separate terumah before one brings in the granary. This represents the Rambam's understanding of the Tosefta, Terumot 1:9 (Kessef Mishneh).

הלכה טו
הָעַכּוּ''ם שֶׁהִפְרִישׁ תְּרוּמָה מִשֶּׁלּוֹ דִּין תּוֹרָה שֶׁאֵינָהּ תְּרוּמָה לְפִי שֶׁאֵינָן חַיָּבִין. וּמִדִּבְרֵיהֶן גָּזְרוּ שֶׁתִּהְיֶה תְּרוּמָתוֹ תְּרוּמָה מִשּׁוּם בַּעֲלֵי כִּיסִין. שֶׁלֹּא יִהְיֶה זֶה הַמָּמוֹן שֶׁל יִשְׂרָאֵל וְיִתְלֶה אוֹתוֹ בְּעַכּוּ''ם כְּדֵי לְפָטְרוֹ. וּבוֹדְקִין אֶת הָעַכּוּ''ם שֶׁהִפְרִישׁ תְּרוּמָה אִם אָמַר בְּדַעַת יִשְׂרָאֵל הִפְרַשְׁתִּיהָ תִּנָּתֵן לְכֹהֵן. וְאִם לָאו טְעוּנָה גְּנִיזָה שֶׁמָּא בְּלִבּוֹ לַשָּׁמַיִם. בַּמֶּה דְּבָרִים אֲמוּרִים בְּאֶרֶץ יִשְׂרָאֵל. אֲבָל עַכּוּ''ם שֶׁהִפְרִישׁ תְּרוּמָה בְּחוּצָה לָאָרֶץ לֹא גָּזְרוּ עֲלֵיהֶן וּמוֹדִיעִין אוֹתוֹ שֶׁאֵינוֹ צָרִיךְ וְאֵינָהּ תְּרוּמָה כְּלָל:
כסף משנה
15.
When a gentile separates terumah from his own produce, according to Scriptural Law, the separation is not effective, because he is not obligated to do so.45See Chapter 1, Halachah 11. This ruling could be understood as a reversal of the Rambam's position in his Commentary to the Mishnah (Terumot 3:9). There he writes that although the gentiles are not obligated to fulfill the mitzvot, if they do, their deeds are effective and they receive a reward. (See Hilchot Melachim 10:10). [Our Rabbis] decreed that his separation should be effective, because of the wealthy,46See Chapter 1, Halachah 13. [i.e., they were fearful] lest the money belong to a Jew and he say that it belongs to a gentile to make it exempt.
We cross-examine the gentile who separates terumah. If he says: "I separated it so that it should be like a Jew's," we give it to a priest. If not, it should be entombed, for perhaps his intent was [to dedicate it] to heaven.47And hence it is considered like consecrated property and we are forbidden to benefit from it.
When does the above apply? In Eretz Yisrael. Our Sages did not, however, issue a decree if a gentile separates terumah in the Diaspora.48Rabbinic decrees are considered as safeguards and generally, we do not make a safeguard for a safeguard. Hence, since the need to separate terumah in the Diaspora is only a Rabbinic decree, we do not add an additional Rabbinic decree and consider the gentile's separation effective (Radbaz). We tell him that he is not obligated to do this and the produce is not terumah at all.

הלכה טז
הַמִּתְכַּוֵּן לוֹמַר תְּרוּמָה וְאָמַר מַעֲשֵׂר. מַעֲשֵׂר וְאָמַר תְּרוּמָה. לֹא אָמַר כְּלוּם. עַד שֶׁיִּהְיֶה פִּיו וְלִבּוֹ שָׁוִין. הִפְרִישׁ תְּרוּמָה בְּמַחֲשַׁבְתּוֹ וְלֹא הוֹצִיא בִּשְׂפָתָיו כְּלוּם הֲרֵי זוֹ תְּרוּמָה שֶׁנֶּאֱמַר (במדבר יח כז) "וְנֶחְשַׁב לָכֶם תְּרוּמַתְכֶם כַּדָּגָן מִן הַגֹּרֶן" בְּמַחֲשָׁבָה בִּלְבַד תִּהְיֶה תְּרוּמָה:
כסף משנה
16.
When a person [makes a separation and] intends to say terumah, but instead says tithes, or intends to say tithes, but instead says terumah, his statement is of no consequence unless his mouth and his heart are in accord.49For the separation of terumah is equivalent to a vow and when making a vow, one's intent and one's statements must be in accord (Siftei Cohen 331:75).
If one separates terumah in his mind without uttering anything verbally, the separation is effective, as [implied by Numbers 18:27]: "And your terumah will be considered50Venechshav translated as "considered" shares the root chashav meaning "thought," thus leading to the interpretation (Beitzah 13b) that terumah can be separated through thought alone. See also the notes to Chapter 3, Halachah 4. for you as the terumah of the granary." Through thought alone, it becomes terumah.

הלכה יז
הַמַּפְרִישׁ תְּרוּמָה עַל תְּנַאי אִם נִתְקַיֵּם הַתְּנַאי הֲרֵי הִיא תְּרוּמָה. וְאִם לָאו אֵינָהּ תְּרוּמָה. וְכֵן הַמַּפְרִישׁ תְּרוּמָה וּמַעַשְׂרוֹת וְנִחָם עֲלֵיהֶן הֲרֵי זֶה נִשְׁאַל לְחָכָם וּמַתִּיר לוֹ כְּדֶרֶךְ שֶׁמַּתִּירִין לוֹ שְׁאָר נְדָרִים. וְתַחֲזֹר חֻלִּין כְּמוֹ שֶׁהָיְתָה עַד שֶׁיַּפְרִישׁ פַּעַם שְׁנִיָּה אוֹתָהּ שֶׁהִפְרִישׁ תְּחִלָּה אוֹ פֵּרוֹת אֲחֵרוֹת:
כסף משנה
17.
[The following rules apply when a person] separates terumah with a stipulation. If the stipulation is fulfilled, the separation is effective. If not, it is not effective.51This principle is derived from the law stated in the following halachah (Kessef Mishneh).
When a person separates terumah and/or the tithes and then regrets [his act], he may approach a sage and ask for its repeal as other vows are repealed.52See Hilchot Nedarim 4:5. The produce then reverts to being ordinary produce as it was before53Based on Nedarim 59a, the Kessef Mishneh explains that this halachah applies only when the terumah has not yet been given to a priest or the tithes to a Levite. If these portions have already been given, there is no way the separations can be retracted. until he makes a separation a second time, [setting aside] either the same produce he separated initially or other produce.

הלכה יח
הַתּוֹרֵם בּוֹר שֶׁל יַיִן וְאָמַר הֲרֵי זוֹ תְּרוּמָה עַל מְנָת שֶׁתַּעֲלֶה שָׁלֵם [צָרִיךְ שֶׁתַּעֲלֶה] שָׁלֵם מִן הַשֶּׁבֶר וּמִן הַשְּׁפִיכָה אֲבָל לֹא מִן הַטֻּמְאָה. וְאִם נִשְׁבְּרָה אֵינָהּ מְדַמַּעַת. הִנִּיחָהּ בְּמָקוֹם שֶׁאִם תִּשָּׁבֵר שָׁם אוֹ תִּתְגַּלְגֵּל לֹא תַּגִּיעַ לַבּוֹר הֲרֵי זוֹ מְדַמַּעַת שֶׁכְּבָר נִתְקַיֵּם הַתְּנַאי:
כסף משנה
18.
[The following rules apply when a person] separates terumah from a cistern of wine, saying: 54I.e., he lets down a utensil into the cistern, allows it to fill, and makes the stipulation cited. Making the stipulation is desirable so that if the terumah falls back into the cistern - because the container breaks or because the wine spills from it - it does not cause the remaining wine to become meduma (mixed with terumah). As indicated by the following halachah, it is preferable to do this - instead of separating the terumah after the container has been lifted from the cistern, so that the terumah and the produce from which it is being separated will be in the same location (see Chapter 3, Halachah 17). "Behold [the contents of] this [container] are terumah on the condition that it ascends intact [from the cistern]," [for the condition to have been met, the container] must ascend intact from being broken or spilt. [The stipulation does not cover the wine] becoming impure.55Since this is not a frequent occurrence, we do not assume the person had it in mind when he made the stipulation. If [the container] is broken [and the wine] spills back into the cistern, it does not cause the mixture to become meduma.56The term meduma refers to a mixture of terumah and ordinary produce, as explained in Chapter 13, Halachah 2. In this instance, although the wine in the container flows back into the cistern after it was designated as terumah, since that designation was made conditionally and the condition was not fulfilled, the wine separated is not considered as terumah. Hence the mixture is not meduma. If [he lifted the container from the cistern and] put it in a place where if it breaks or rolls, it will not reach the cistern, [should the wine later spill into the cistern], it causes the mixture to become meduma, because the stipulation was fulfilled.

הלכה יט
בַּמֶּה דְּבָרִים אֲמוּרִים בִּתְרוּמָה גְּדוֹלָה. אֲבָל בִּתְרוּמַת מַעֲשֵׂר שֶׁמֻּתָּר לִתְרֹם שֶׁלֹּא מִן הַמֻּקָּף כֵּיוָן שֶׁעָלְתָה נִתְקַיֵּם תְּנָאוֹ וַהֲרֵי הִיא תְּרוּמַת מַעֲשֵׂר וְאַף עַל פִּי שֶׁנִּשְׁבְּרָה אוֹ שֶׁנִּשְׁפְּכָה וְאֵין צָרִיךְ לוֹמַר שֶׁנִּטְמֵאת:
כסף משנה
19.
When does the above apply? With regard to the great terumah.57For, as mentioned above, the terumah and the produce from which it is being separated should be in the same location. With regard to terumat ma'aser, by contrast, [different rules apply] because it is permitted to make this separation from produce that is not in the same place.58See Chapter 3, Halachah 20. [Hence as soon as the container] ascends [from the cistern], his stipulation is considered to have been fulfilled and [the wine separated] is terumat ma'aser, even though [afterwards, the container] breaks or [the wine] spills.59The rationale for the Rambam's ruling can be explained as follows: Terumat ma'aser can be separated when the produce is not in the same place as the produce for which it is being separated. Hence, were the person making the separation to be concerned that the produce separated as terumat ma'aser might fall into the cistern, he should have made the separation outside the cistern. The fact that he did not do so, nor make a specific statement acknowledging this possibility in his stipulation shows that this was not the intent motivating his stipulation. Hence, as soon as the container ascends from the cistern, his condition is met, even if the wine spills back in afterwards. Needless to say, this applies if [the terumat ma'aser] becomes impure.

הלכה כ
הָאוֹמֵר שֶׁלְּמַעְלָה תְּרוּמָה וְשֶׁלְּמַטָּה חֻלִּין אוֹ שֶׁלְּמַעְלָה חֻלִּין וְשֶׁלְּמַטָּה תְּרוּמָה דְּבָרָיו קַיָּמִין שֶׁהַדָּבָר תָּלוּי בְּדַעַת הַתּוֹרֵם:
כסף משנה
20.
When a person says: "The produce in the upper portion [of this container] is terumah and that in its lower portion is ordinary produce" or "The produce in the upper portion [of this container] is ordinary produce and that in its lower portion is terumah," his statements are effective.60I.e., even though physically, the produce was not separated, since a separation was made in the mind of the owner, it is sufficient and it is permitted to eat from the portion of the produce that is designated as "ordinary." For the matter is dependent on the thought of the person making the separation.

הלכה כא
הַתּוֹרֵם אֶת הַגֹּרֶן צָרִיךְ שֶׁיְּכַוֵּן אֶת לִבּוֹ שֶׁתִּהְיֶה זוֹ תְּרוּמָה עַל הַכְּרִי וְעַל מַה שֶׁבַּקּוּטְעִין וְעַל מַה שֶּׁבַּצְּדָדִין וְעַל מַה שֶּׁבְּתוֹךְ הַתֶּבֶן. הַתּוֹרֵם אֶת הַיֶּקֶב צָרִיךְ שֶׁיְּכַוִּן אֶת לִבּוֹ לִתְרֹם עַל מַה שֶּׁבַּחַרְצַנִּין וְעַל מַה שֶּׁבַּזַּגִּין. הַתּוֹרֵם אֶת הַבּוֹר שֶׁל יַיִן צָרִיךְ שֶׁיְּכַוֵּן אֶת לִבּוֹ לִתְרֹם עַל מַה שֶּׁבַּגֶּפֶת. וְאִם לֹא נִתְכַּוֵּן אֶלָּא תָּרַם סְתָם נִפְטָר הַכּל. שֶׁתְּנַאי בֵּית דִּין הוּא שֶׁהַתְּרוּמָה עַל הַכּל. הַתּוֹרֵם כַּלְכָּלָה שֶׁל תְּאֵנִים וְנִמְצְאוּ תְּאֵנִים בְּצַד הַכַּלְכָּלָה הֲרֵי אֵלּוּ פְּטוּרִין מִפְּנֵי שֶׁבְּלִבּוֹ לִתְרֹם עַל הַכּל:
כסף משנה
21.
When a person separates terumah from [grain in] a granary, he must have the intent in his heart that [the produce separated] will be terumah for this grain heap, the stalks of wheat that were cut [and not threshed], [the grain] on the side of the grain heap, and [the kernels] in the straw.61In his Commentary to the Mishnah (Ma'aserot 5:4), the Rambam writes that the intent is that he should separate terumah for the entire crop, that which he sees and that which he does not see. When a person separates terumah from a vat [of wine], he must have the intent in his heart that he is separating terumah for [the wine absorbed] in the kernels and the peels.
When a person separates terumah from a cistern of wine,62When quoting this law, the Shulchan Aruch (Yoreh De'ah 331:50) speaks of a vat of oil. There are some who maintain that the wording in the Mishneh Torah should also read in that manner. Nevertheless, the authoritative manuscripts and early printings of the Mishneh Torah read as above. he must have the intent in his heart that he is separating terumah for [the wine absorbed] in the peat.63I.e., the dregs. In truth, the term gefet is used more frequently in connection with oil than with wine. [in all the above instances,] if he separates terumah without having a specific intent, all of the produce is included. For it is a condition of the court that [when one separates terumah, it] includes everything.64Hence, since we assume that every Jew desires to perform the mitzvot in keeping with our Sages' desires, it is as if the person separating the terumah had this intent in mind. Preferably, however, a person should consciously have such thoughts when separating terumah. When a person separates terumah from a basket of figs and other figs are found at the side of the basket, terumah need not be separated from them, because in his heart, a person has the intent to separate terumah for all the produce.

זרעים הלכות תרומות פרק ד
Zeraim Terumos Chapter 4