daf bit: Erchin 6

It was taught in one baraita (a teaching contemporary with the mishna): if an idol-worshipper offers a freewill gift toward Temple repairs one accepts it from him, while another baraita teaches that one does not. R. Ela said in the name of R. Yochanan: there is no difficulty; the first refers to the beginning of a project, when we are concerned about the idol-worshipper's intentions, while the second refers to the end of the project. He holds, though, that even at the end one cannot accept a gift that can be easily identified, lest the idol-worshipper point boastfully to his contribution.

R. Yosef raised an objection, citing a case where an agent of the (secular) king made a donation, but Abaye said it is different with the government because they do not retract (its gift stays given). (6a)

Abaye's point suggests that the first baraita is concerned (at least in part) with the idol-worshipper retracting his gift later (once it has been put to use, perhaps). As for "the government does not retract what it gives", may it be so in our time!