And thou shalt say unto Pharaoh, Thus saith the LORD, Israel is my son, even my firstborn:
22. Israel is my son, even my first-born. God thus refutes, by anticipation, the only pretext by which Pharaoh could justify his refusal to let the people go. For Jacob had spontaneously submitted himself and all his family to his government; he had then free power to retain the people, which, by the common law of nations, was subject to the dominion of Egypt.
Moses honored his father-in-law by asking leave before departing, showing that divine commission does not free us from the duties we owe in our station. God knew the secret fear that held him back, dread of his old enemies, and assured him the way was clear.
AI summary
Commenting on Exodus 4:18-23
And thou shall say unto Pharaoh,.... When arrived in Egypt, and in his presence: thus saith the Lord; he was to declare to him that he came in his name, and by his orders, and, as an ambassador of his, required the dismission of the children of Israel out of Egypt: Israel is my son, even my firstborn; as dear to him as a man's...