Charles Ellicott Commentary Exodus 4:20

"And Moses took his wife and his sons, and set them upon an ass, and he returned to the land of Egypt: and Moses took the rod of God in his hand." — Exodus 4:20 (ASV)

His sons. — Only one had been mentioned previously, namely, Gershom (Exodus 2:22), unless we accept the Vulgate addition to that place. But another had been recently born to him.

Set them upon an ass. — Hebrew, upon the ass, that is, either “upon his ass,” or, according to some, “upon asses.” The singular of a substantive with the article is sometimes used for the genus (Genesis 15:11).

He returned. — Rather, set out to return (ἐπέστρεψεν, Septuagint).

The rod of God. — An emphatic phrase. God’s endowment of the rod with miraculous power had made it “the rod of God.” It was the instrument by means of which most of the plagues and the other miracles were performed (Exodus 7:20; Exodus 8:6; Exodus 8:17; Exodus 9:23; Exodus 10:13; Exodus 14:16; Exodus 17:5; Numbers 20:9; and others).