Goest to return— Houbigant renders this, And the Lord said unto him, when he was returning into Egypt. The Vulgate renders it in the same manner.
I will harden his heart— For a full explication of this phrase, see the note on ch. Exodus 9:34.
Related Commentaries of Exodus 4:21
Exodus 4:21
21 And the LORD said unto Moses, When thou goest to return into Egypt, see that thou do all those wonders before Pharaoh, which I have put in thine hand: but I will harden his heart, that he shall not let the people go.