Exodus 18:6

And he said unto Moses, I thy father in law Jethro am come unto thee, and thy wife, and her two sons with her.

Jethro sent word ahead to Moses that he had arrived bringing Moses' wife and her two sons with her. He had come to visit after hearing of Israel's deliverance and to restore Moses' family to him. Moses had sent them away while facing the dangers and demands of leading Israel out of Egypt, and he welcomed their return with joy.

He had sent his wife back to Midian while on the way to Egypt to spare her the pain of witnessing the judgments to fall upon the Egyptians. The wife thus brought back to him was Zipporah, a Midianite and therefore a descendant of Abraham and a worshiper of the true God, of timid, retiring, gentle and affectionate disposition and somewhat darker in complexion than the Hebrews. Jethro himself was singled out from the Gentile world to reveal the principles of heaven and to serve as a witness for God.

When Zipporah saw that Moses' burdens were wearing away his strength she made her fears known to Jethro, and Jethro then suggested measures for his relief. Miriam regarded Zipporah as the cause of supposed neglect toward herself and Aaron, concluding that Zipporah's influence had kept Moses from taking them into his counsels as formerly. This was the chief reason for Miriam's antipathy to Zipporah.