Halakha Ulangan 23:22: Mishneh Torah, Gifts to the Poor, Shulchan Arukh, Choshen Mishpat, Kitzur Shulchan Arukh & Sefer HaMitzvot

A [pledge to] tzedakah is a form of a vow, and therefore one who says, "I pledge to give a selah for tzedakah," or "This selah is for tzedakah" is obligated to give it to the poor immediately,¹⁴⁴See Babylonian Talmud Rosh Hashanah 6a. and if he delays, then he has transgressed the commandment not to delay [fulfilling a vow] (Deut. 23:22). Thus, if poor people can be found there [when he makes the vow], he should give it [to them] immediately. If there are no poor people there, he should set it aside and leave it until he happens upon some poor people. But if he stipulates that he will not give [the coin] until he encounters a poor person, then he need not set it aside. So also if he makes the condition at the time he took the vow for tzedakah or to donate something that the collectors are permitted to exchange it or to change it with a goldsmith, then they are permitted to do so.

If the litigant argues that the arbitrators who ordered him to act [in accordance with their decision] did not fix a time limit for him [to carry out their decision] and that he will act [accordingly] as soon as [the matter] will come to hand, what he says is considered void, but he must carry out [the decision] forthwith.³⁴RaShBA. Cf. Ned. 3b: ‘How is thou shalt not delay to pay it (Deut. XXIII, 22) with regards to Neziruth, applicable? For as soon as he says, Behold I am a Nazir, he becomes a Nazir; if he eats (grapes), he violates, neither shall he … eat moist grapes or dried (Num. VI, 3) ? — When he says, When I wish I will become a Nazir. But if he says, When I wish, the Biblical injunction, thou shalt not delay is not applicable? — Said Raba, e.g., If he says, I must not leave the world before having been a Nazir, for he becomes a Nazir from that very moment. This is similar to one who says to his wife, Behold here is your bill of divorce (to become effective) one hour prior to my death in which case she is straightway forbidden to eat Terumah. Hence, we say that he may die any moment. Consequently, here too, (regarding a Nazir) he becomes a Nazir at once, because we say, Perhaps he will die now.’ Thus we see that when one undertakes to fufil something without mentioning any specified time, it takes effect immediately. Consequently, the same principle operates in the present ruling. Cf. also Sifra to Lev. XV, 25. Once the arbitrators state their decision before the litigants, they must not make any changes, for their commission is then considered completed. However, as long as they have not stated their decision before them, although they had stated it before the witnesses or others, they may still make changes according to their discretion — Birkath Ya‘akob.

Charity is in the category of vows. Therefore, if you say, "I will donate money to charity" or "this coin is charity" you must immediately give it to the poor, and if you delay [giving it to them] you are in violation of the commandment, "You must not delay,"²⁵Deuteronomy 23:22. because you could have given it immediately. If there are no poor people available, you may set the money aside until you find some poor people. If you pledge charity in the synagogue which is to be entrusted to the treasurer, you are not in violation²⁶You are not in violation of the law stated above, that you must immediately give it to the poor. until the treasurer demands the money. Then [if you do not give it] you are immediately in violation; unless you know that he doesn't need the money for immediate [distribution] but will merely hold it in his possession.