daf bit: Avodah Zarah 2
New tractate -- onward to idolatry! Today's daf is 3, but we'll start with the mishna that begins 2.
The mishna says: on the three days preceding the festivities of idolaters, it is forbidden to do business with them, to lend or borrow articles with them, to advance or receive money from them, or to repay a debt or receive repayment. A note in the Soncino edition says this restriction is lest any benefit to them from these activities lead to them rejoicing before their idols -- it would be as if we contributed to that idolatry. R' Yehudah says we should receive repayment from them as this can only depress them, but the rabbis say even if it is depressing at the time, in the end they are glad of it. (2a) Later the g'mara gives another reason: we avoid receiving as an extra protection against giving/lending.