כִּֽי־נָשְׂא֣וּ מִבְּנֹֽתֵיהֶ֗ם לָהֶם֙ וְלִבְנֵיהֶ֔ם וְהִתְעָֽרְבוּ֙ זֶ֣רַע הַקֹּ֔דֶשׁ בְּעַמֵּ֖י הָאֲרָצ֑וֹת וְיַ֧ד הַשָּׂרִ֣ים וְהַסְּגָנִ֗ים הָֽיְתָ֛ה בַּמַּ֥עַל הַזֶּ֖ה רִאשׁוֹנָֽה׃ (ס)
Rashi on Ezra
was first in this treachery for they commenced to deal treacherously by intermarrying with the peoples of the lands.