Why Moses Swore an Oath to Jethro and Named Zipporah

"And Moses was content (va-yo'el)" — that he swore an oath to him, just as Jacob swore to Laban, as it is written, "if you afflict my daughters" (Genesis 31:50), [meaning] concerning marital relations. For va-yo'el means nothing other than the language of an oath, as it is said, "And Saul adjured (va-yo'el) the people, saying" (1 Samuel 14:24). Another interpretation: "And Moses was content to dwell" — Moses accepted upon himself to dwell with him, for va-yo'el means nothing other than the language of dwelling, as it is said, "Be content (ho'el) now and lodge" etc. (Judges 19:6). "And he gave Zipporah his daughter to Moses." And why was her name called Zipporah? Because she ran like a bird (tzippor). Another interpretation: because she purified her father's house from idolatry, like the priest who purifies with the blood of the bird (tzippor).