Charles Ellicott Commentary Exodus 18:2

"And Jethro, Moses` father-in-law, took Zipporah, Moses` wife, after he had sent her away," — Exodus 18:2 (ASV)

He does not simply judge— that is, decide the particular question brought before him; but he takes the opportunity to educate and instruct the people in delivering his judgments—he makes them know the statutes of God and His laws—he expounds principles and teaches morality. Both reasons were clearly of great weight, and constituted strong arguments in favour of his practice.