레위기 27:26의 시프레이 미츠보트

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.

One who connects pledges of tzedakah is as obligated with one vow as with another. How so? [This applies] if he said, "This selah is like that selah, then that one is for tzedakah." If he sets aside a selah and said, "This is for tzedakah," and then he took out a second selah and said, "And this second one is for tzedakah" even though he did not set it aside from the start.¹⁴⁵See Babylonian Talmud Nedarim 7a.

One who took a vow for tzedakah without knowing how much he vowed should give until he says, "This is not what I intended."¹⁴⁶See Mishnah Menachot 13:4.