וְלָקַחְתָּ֥ מִבְּנֹתָ֖יו לְבָנֶ֑יךָ וְזָנ֣וּ בְנֹתָ֗יו אַחֲרֵי֙ אֱלֹ֣הֵיהֶ֔ן וְהִזְנוּ֙ אֶת־בָּנֶ֔יךָ אַחֲרֵ֖י אֱלֹהֵיהֶֽן׃
и ты берешь их дочерей к своим сыновьям, и их дочери сбиваются с пути за своих богов и сбивают с пути своих сыновей за своих богов.
Mishneh Torah, Foreign Worship and Customs of the Nations
It is forbidden to partake of a wedding feast which an idolater makes for his son or his daughter; even to eat or drink one's own is forbidden to an Israelite, as it would be eating in company of idolaters. Whenceonward is it forbidden to eat with such an idolater? From the commencement of preparation for the feast, the entire duration of the feast, and thirty days thereafter. If the idolater make a special feast in honor of such nuptials, even after the lapse of thirty days, it is forbidden to eat with him until the lapse of twelve months. All this distant separation is ordained because of idolatry, even as it is said: "And one call thee, and thou art of his sacrifice. And lest thou take of his daughters unto thy sons…. and when his daughters go astray after their gods" (Ex. 34.15–16).19Ibid. 8a.C.