Charles Ellicott Commentary Exodus 18:4

"and the name of the other was Eliezer; for [he said], The God of my father was my help, and delivered me from the sword of Pharaoh." — Exodus 18:4 (ASV)

Eliezer. —Eliezer is supposed to have been the boy whom Zipporah circumcised in the wilderness (Exodus 4:25). He grew to manhood and had a son, Rehabiah (1 Chronicles 23:17), whose descendants were in the time of David very numerous (1 Chronicles 23:17; and compare to 1 Chronicles 26:25–26). It is uncertain whether Moses gave him his name before parting from him, in allusion to his escape from the Pharaoh who sought to slay him (Exodus 2:15), or first named him on occasion of receiving him back, in allusion to his recent escape from the host that had been destroyed in the Red Sea.