Ezra 9:1-2
Now when these things were done, the princes came to me, saying, The people of Israel, and the priests, and the Levites, have not separated themselves from the people of the lands, doing according to their abominations, even of the Canaanites, the Hittites, the Perizzites, the Jebusites, the Ammonites, the Moabites, the Egyptians, and the Amorites. For they have taken of their daughters for themselves, and for their sons: so that the holy seed have mingled themselves with the people of those lands:
Deuteronomy 7:3-4
Neither shalt thou make marriages with them; thy daughter thou shalt not give unto his son, nor his daughter shalt thou take unto thy son. For they will turn away thy son from following me, that they may serve other gods: so will the anger of the LORD be kindled against you, and destroy thee suddenly.
Ezra's devastating confession is grounded in the Deuteronomy 7 intermarriage prohibition. The princes' report catalogs the same nations that Deuteronomy 7:1 names as the statutory targets of covenant separation — Canaanites, Hittites, Perizzites, Jebusites, Amorites — confirming that the returning community has violated the precise statutory boundary Moses established. Ezra's horror is proportionate to the statutory gravity: this is not a minor covenant lapse but the direct violation of the foundational separation ordinance that sustained covenant identity.