הלכה על עבודה זרה 67:10

He prohibited us from drinking wine of (an idolatrous) libation. But this does not appear explicitly explained in Scripture. However He does say about idolatry, "Those that did eat the fat of their sacrifices, and drank the wine of their drink offerings" (Deuteronomy 32:38) - [hence] just like the sacrifice is forbidden, so [too] is wine forbidden. And you know that it is forbidden to benefit [from it] and that we give lashes for it, as it is made known in the Talmud. And the proof of wine of a libation being forbidden, that its prohibition is from Torah law and that it is counted among the negative commandments, is their saying in Avodah Zarah (Avodah Zarah 73b), "Rabbi Yochanan and Reish Lakish both say, 'Anything forbidden by the Torah [that falls into a mixture] - whether of its own type or another type - [is forbidden where there is enough of the forbidden item] to impart flavor; except untithed produce and wine of a libation, which [render it forbidden] with any amount when with its type; but [only where] it imparts flavor when with another type.'" And this is an explicit proof that the wine of a libation is from the prohibitions of the Torah. And also in the Sifrei (Sifrei Bamidbar 131:2), when it illustrated the description of the Israelites spreading out at Shittim to be involved in licentiousness with the daughters of Moav, they said, "He would enter and the pitcher near her was full of Ammonite wine - the wine of idolaters having not yet been forbidden to Israelites. She said, 'Would you like to drink, etc.?'" Behold from their saying, "the wine of idolaters having not yet been forbidden to Israelites," there is a proof that after this [in the Torah], without a doubt, it was forbidden. However their saying (Shabbat 17b) that among the eighteen things that they decreed, among them was wine; as well as their saying (Avodah Zarah 34a), "It is different, wine of a libation is rabbinic" - the intention was [about] the unspecified wine of gentiles, and not the wine of a libation itself. But the wine of a libation itself is surely forbidden by the Torah. And you already know their saying (Avodah Zarah 30b), "There are three wines, etc." And the regulations of this commandment have already been explained in the last chapters of Avodah Zarah. (See Parashat Haazinu; Mishneh Torah, Forbidden Foods 1.)