Tosefta for Numbers 5:29

זֹ֥את תּוֹרַ֖ת הַקְּנָאֹ֑ת אֲשֶׁ֨ר תִּשְׂטֶ֥ה אִשָּׁ֛ה תַּ֥חַת אִישָׁ֖הּ וְנִטְמָֽאָה׃

This is the law of jealousy, when a wife, being under her husband, goeth aside, and is defiled;