Arachin 6 - Money for Charity
If an idolater separated a Kohen’s portion (terumah) from his grain, saying "I wanted to do what Jews do" - this is a valid. However, if he said nothing, then perhaps he meant for the Temple, and since there is no Temple, it has to be hidden. In general, any "consecration for the Temple" today creates a similar problem.
Money designated for charity is similar to a vow: just as a vow has to be fulfilled in its due time, so charity has to be paid; if the time was not specified, it means right away. However, it is not similar to Temple consecration: one can use designated coins, and then repay. One who collects charity - money or objects -from people should be careful to use it according to their designation, unless he knows that they would not mind if he uses it for a different good cause.
One who is in the throes of death and one who is going out to be executed by court cannot be a subject of any monetary vow. But the condemned should at least have a symbolic value!? - Since there is not redemption for a murderer, by analogy there is none for the condemned one.
Art: Camille Pissarro - Charity