Someone came my door collecting money for a charity. I went to get some money, but when I returned to the door, he was gone.

Q: Am I obligated to search for the collector to give him the money?

A: There is a debate whether someone who pledges to give money to a particular poor person may change his mind and give that money to another poor person. It is certain that he must give that amount of money to tzedakah, since a pledge to give to the poor is comparable to a vow (Y.D. 258:12). But must he give it to the original person, or will giving it to someone else fulfill his obligation?

One understanding of the Gemara (Arachin 6a) is that one who pledges money to tzedakah may “change it,” i.e. give elsewhere, as long as the money did not yet reach the possession of the tzedakah administrator (see Tosafos Arachin 6b, d”h ad; Maharit 1:39). Others contend that the Gemara is merely permitting an exchange of one set of coins for another or borrowing the pledged funds, but does not allow one to redirect the money to another poor person (see Tosafos ibid. and Ketzos 87:22).

The point of dispute is whether the principle amirah l’gavo’ah k’mesirah l’hedyot (just as an act of acquisition transfers ownership of an object between private people, so too a declaration to consecrate something to the Beis Hamikdash transfers ownership of that object), applies to a pledge of tzedakah.

Many authorities maintain that the principle does not apply to tzedakah pledges (Ketzos 66:2, 255:2 and 257:1). Others maintain that the principle does apply to tzedakah pledges, and once one pledged to give tzedakah to a particular needy person, he is not permitted to give that money to someone else (Machaneh Ephraim, Tzedakah 7; Shach, C.M. 87:51; Ketzos 87:21; and Chasam Sofer, Y.D. 237).

Some authorities contend that this is true only when someone pledged a particular object to a particular recipient, which, when the pledge was made, transferred ownership of that object to the intended recipient. However, if he pledged money, he may give that amount of money to someone else, since there is no object for the recipient to acquire (Tumim 87:21).

Others disagree with this and maintain that the pledge to give money to a particular person generates a shibud (lien) on the donor’s possessions that cannot be taken away from the recipient and given to someone else (Ketzos, ibid.; see Ketzos 212:4 and Pischei Teshuvah 212:9).

In your case, since you actually took out money for the collector, the halacha is subject to the above question of amirah l’gavo’ah k’mesirah l’hedyot. Even according to the lenient opinion you must give that money to tzedakah. However, two considerations may permit you to keep the money for yourself.

In cases of necessity, one may follow those authorities who rule that one may rely on the declaration of intent that we make before Rosh Hashanah, indicating that our vows should not be binding. Although one who makes a vow may not rely on that, in a case where one’s pledge is treated by Chazal as a vow, it may be relied upon (Salmas Chaim 2:38; Minchas Shlomo 1:91:20). However, one should generally adopt a stringent position concerning this matter (Halichos Shlomo, Tishrei, pp. 7, 387). Accordingly, l’chat’chila one should avoid making a definitive decision to give a particular person tzedakah but rather intend that the money not transfer to that person until it physically reaches him.

Also, Kesef HaKodashim (125:5) suggests that it is understood that the donor only intends for the pledge to be binding once he finds the poor person.