Reference for Avodah Zarah 1:1
לִפְנֵי אֵידֵיהֶן שֶׁל גּוֹיִם שְׁלשָׁה יָמִים אָסוּר לָשֵׂאת וְלָתֵת עִמָּהֶן, לְהַשְׁאִילָן וְלִשְׁאֹל מֵהֶן, לְהַלְוֹתָן וְלִלְוֹת מֵהֶן, לְפָרְעָן וְלִפָּרַע מֵהֶן. רַבִּי יְהוּדָה אוֹמֵר, נִפְרָעִין מֵהֶן מִפְּנֵי שֶׁהוּא מֵצֵר לוֹ. אָמְרוּ לוֹ, אַף עַל פִּי שֶׁמֵּצֵר הוּא עַכְשָׁיו, שָׂמֵחַ הוּא לְאַחַר זְמָן:
Three days before "ideihen" [(an epithet for "their festivals")] of the idolators it is forbidden to trade with them [(to sell or to buy) because they go and thank their gods (for it) on the day of their festival], to lend them [animals or vessels, things that are returned intact] or to borrow from them; to lend them [money, which is not returned intact, loans being given to be spent] or to borrow (money) from them; to pay them (a debt) [When they are paid they go and thank their god on their holiday], or to exact payment from them. R. Yehudah said: Payment may be exacted of them for they are distressed [over their lost money and will not go and thank (their god).] They said to him: Even though they are distressed now, they will be happy afterwards [on the morrow, the day of their festival, and will go and thank (their god). The halachah is not in accordance with R. Yehudah. And it is only for a written loan that it is forbidden to exact payment of them; but for a verbal loan it is permitted, it being considered as rescuing (his money from their hand)]