וַיְהִ֖י כְּשָׁמְעָ֣ם אֶת־הַתּוֹרָ֑ה וַיַּבְדִּ֥ילוּ כָל־עֵ֖רֶב מִיִּשְׂרָאֵֽל׃
И когда они услышали закон, то отделили от Израиля всю смесь пришельцев.
Ibn Ezra
…God’s community meaning, he shall not be considered as one of God ’s community for purposes of marriage to an Israelite woman [Qiddushin 72b–73a]. The same applies to an Ammonite (but not an Ammonitess), and a Moabite (but not a Moabitess).