let his father in law depart
18:27 let his father in law depart. Moses had left his family with Jethro when he returned to Egypt to lead the Israelites to freedom. (Exodus 18:2). At this point, however, his wife Zipporah rejoined him, with their two sons Gershom and Eliezer (see Exodus 18:2-4). Apparently she had started with Moses to Egypt, but returned to Jethro after the circumcision of her son (Exodus 4:20,24-26). So far as the record goes, Zipporah thenceforth stayed with Moses and the Israelites.