Halakha Ulangan 7:3: Mishneh Torah, Forbidden Intercourse, Shulchan Arukh, Even HaEzer, Mishneh Torah, Negative Mitzvot & Sefer HaChinukh

If a Jewish person sleeps with a non-Jew in the way of married people, they receive biblically ordained lashes, as it says “You shall not intermarry with them: do not give your daughter to their sons or take their daughters for your sons.” (Deuteronomy 7:3) The same law is true concerning the seven nations of the land of Canaan and all other nations. This is also explained by Ezra, “We will not give our daughters in marriage to the peoples of the land, or take their daughters for our sons.” (Nehemiah 10:31)

If a Jew engages in sexual relations with a female idolater, derech ishut (that is, for the purpose of marriage), or a Jewess engages in sexual relations with a male idolater, that Jew or Jewess is given lashes on a Biblical level. As it is written (Deuteronomy 7:3): "You shall not marry them." (There are those who disagree with this ruling). However, if he engages in sexual relations derech zenut (that is, for licentiousness), casually, he is culpable only on a Rabbinic level for idolatry and for engaging in relations with a prostitute and he is given makat mardut (that is, lashes on a Rabbinic level). And, if he sets her aside for licentious activity, he is culpable on a Rabbinic level for having sexual relations with a nida (that is, menstruant), having sexual relations with a shifcha, (that is, slavewoman), idolatry, and having sexual relations with a prostitute. And, if he is a Kohen (that is, a priest), even if he engages in sexual relations casually, he receives lashes on a Biblical level, as it is written (Leviticus 21:7) ["(A kohen) may not marry a prostitute..."]

Not to show favour to idolaters, as it is said, “Nor show them favour” (Deut. 7:2).