Albert Barnes Commentary Exodus 18:1

"Now Jethro, the priest of Midian, Moses` father-in-law, heard of all that God had done for Moses, and for Israel his people, how that Jehovah had brought Israel out of Egypt." — Exodus 18:1 (ASV)

Jethro was, in all probability, the “brother-in-law” of Moses (Exodus 3:1). On the parting from Zipporah, see (Exodus 4:26).