If, by contrast, a Jewish male enters into relations with a gentile woman, when he does so intentionally, she should be executed.23 She is executed because she caused a Jew to be involved in an unseemly transgression, as [is the law with regard to] an animal.24 [This applies regardless of] whether the gentile women was a minor of three years of age,25 or an adult, whether she was single or married. And it applies even if [the Jew] was a minor of nine years old, [she is executed].26
This [punishment] is explicitly mentioned in the Torah, as [Numbers 31:16-17] states: "Behold they were [involved] with the children of Israel according to the advice of Balaamו.27 Execute any woman fit to know a man through lying with a male."
23. Note the gloss of the Maggid Mishneh who questions the source for the Rambam's ruling, arguing that the passage from Numbers cannot be interpreted as definitive proof.
24. See Chapter 1, Halachot 16-18.
25. If, however, she is younger than three, the relations are not considered significant.
26. From that age onward, sexual relations in which he engages are significant, as stated in Chapter 1, Halachah 13.
27. Who advised the Midianites and the Moabites to have their women seduce Jewish men to provoke God's wrath.