Parashas Shemos
וַיּ֥וֹאֶל מֹשֶׁ֖ה לָשֶׁ֣בֶת אֶת־הָאִ֑ישׁ וַיִּתֵּ֛ן אֶת־צִפֹּרָ֥ה בִתּ֖וֹ לְמֹשֶֽׁה׃
Moses consented to stay with the man, and he gave Moses his daughter Zipporah as wife.
Torah Temimah points to TT / Nedarim (verified).
ויואל משה — אין אלה אלא שבועה, דכתיב ויבא אתו באלה.
English: “And Moshe was willing (vayoel)” — this language of alah is nothing other than an oath, as it is written “and he brought him under an oath (alah).”
Custom
Chazal read vayoel as an oath: Moshe bound himself not to depart from Yisro’s household without consent.