Adam Clarke Bible Commentary
Let me go, I pray thee, and return unto my brethren - Moses, having received his commission from God, and directions how to execute it, returned to his father-in-law, and asked permission to visit his family and brethren in Egypt, without giving him any intimation of the great errand on which he was going. His keeping this secret has been attributed to his singular modesty: but however true it might be that Moses was a truly humble and modest man, yet his prudence alone was sufficient to have induced him to observe silence on this subject; for, if once imparted to the family of his father-in-law, the news might have reached Egypt before he could get thither, and a general alarm among the Egyptians would in all probability have been the consequence; as fame would not fail to represent Moses as coming to stir up sedition and rebellion, and the whole nation would have been armed against them. It was therefore essentially necessary that the business should be kept secret.
In the Septuagint and Coptic the following addition is made to this verse: Μετα δε τας ἡμερας τας πολλας εκινας ετελευτησεν ὁ βασιλευς Αιγυπτου· After these many days, the king of Egypt died. This was probably an ancient gloss or side note, which in process of time crept into the text, as it appeared to throw light on the following verse.
John Gill Bible Commentary
And Moses went and returned to Jethro his father in law,.... With his flock of sheep he kept, Exo 3:1, and said unto him:
let me go, I pray thee, and return to my brethren which are in Egypt; the Israelites, who were so by nation and religion; as Jethro had been kind and beneficent to him, he did not choose to leave him without his knowledge and consent, and especially to take away his wife and children without it:
and see whether they be yet alive; it seems by this that Moses had heard nothing of them during the forty years he lived in Midian, which may be thought strange, since it was not very far from Egypt; and besides the Midianites traded in Egypt, as we learn from Gen 37:28 but this must be ascribed to the providence of God, that so ordered it, that there should be no intercourse between him and his brethren, that so no step might be taken by them for their deliverance until the set time was come. Moses did not acquaint his father-in-law with the principal reason of his request, nor of his chief end in going into Egypt, which it might not be proper to acquaint him with, he being of another nation, though a good man; and lest he should use any arguments to dissuade Moses from going, who now having got clear of his diffidence and distrust, was determined upon it: though some ascribe this to his modesty in not telling Jethro of the glorious and wonderful appearance of God to him, and of the honour he had conferred on him to be the deliverer and governor of the people of Israel:
and Jethro said to Moses, go in peace; he judged his request reasonable, and gave his full consent to it, and wished him health and prosperity in his journey.
Matthew Henry Bible Commentary
Here, I. Moses obtains leave of his father-in-law to return into Egypt, Exo 4:18. His father-in-law had been kind to him when he was a stranger, and therefore he would not be so uncivil as to leave his family, nor so unjust as to leave his service, without giving him notice. Note, The honour of being admitted into communion with God, and of being employed for him, does not exempt us from the duties of our relations and callings in this world. Moses said nothing to his father-in-law (for aught that appears) of the glorious manifestation of God to him; such favours we are to be thankful for to God, but not to boast of before men.
II. He receives from God further encouragements and directions in his work. After God had appeared to him in the bush to settle a correspondence, it should seem, he often spoke to him, as there was occasion, with less overwhelming solemnity. And, 1. He assures Moses that the coasts were clear. Whatever new enemies he might make by his undertaking, his old enemies were all dead, all that sought his life, Exo 4:19. Perhaps some secret fear of falling into their hands was at the bottom of Moses's backwardness to go to Egypt, though he was not willing to own it, but pleaded unworthiness, insufficiency, want of elocution, etc. Note, God knows all the temptations his people lie under, and how to arm them against their secret fears, Psa 142:3. 2. He orders him to do the miracles, not only before the elders of Israel, but before Pharaoh, Exo 4:21. There were some alive perhaps in the court of Pharaoh who remembered Moses when he was the son of Pharaoh's daughter, and had many a time called him a fool for deserting the honours of that relation; but he is now sent back to court, clad with greater powers than Pharaoh's daughter could have advanced him to, so that it might appear he was no loser by his choice: this wonder-working rod did more adorn the hand of Moses than the sceptre of Egypt could have done. Note, Those that look with contempt upon worldly honours shall be recompensed with the honour that cometh from God, which is the true honour. 3. That Pharaoh's obstinacy might be no surprise nor discouragement to him, God tells him before that he would harden his heart. Pharaoh had hardened his own heart against the groans and cries of the oppressed Israelites, and shut up the bowels of his compassion from them; and now God, in a way of righteous judgment, hardens his heart against the conviction of the miracles, and the terror of the plagues. Note, Ministers must expect with many to labour in vain: we must not think it strange if we meet with those who will not be wrought upon by the strongest arguments and fairest reasonings; yet our judgment is with the Lord. 4. Words are put into his mouth with which to address Pharaoh, Exo 4:22, Exo 4:23. God had promised him (Exo 4:12), I will teach thee what thou shalt say; and here he does teach him. (1.) He must deliver his message in the name of the great Jehovah: Thus saith the Lord; this is the first time that preface is used by any man which afterwards is used so frequently by all the prophets: whether Pharaoh will hear, or whether he will forbear, Moses must tell him, Thus saith the Lord. (2.) He must let Pharaoh know Israel's relation to God, and God's concern for Israel. Is Israel a servant? is he a home-born slave? Jer 2:14. "No, Israel is my son, my firstborn, precious in my sight, honourable, and dear to me, not to be thus insulted and abused." (3.) He must demand a discharge for them: "Let my son go; not only my servant whom thou hast no right to detain, but my son whose liberty and honour I am very jealous for. It is my son, my son that serves me, and therefore must be spared, must be pleaded for," Mal 3:17. (4.) He must threaten Pharaoh with the death of the first-born of Egypt, in case of a refusal: I will slay thy son, even thy firstborn. As men deal with God's people, let them expect to be themselves dealt with; with the froward he will wrestle.
III. Moses addresses himself to this expedition. When God had assured him (Exo 4:19) that the men were dead who sought his life, immediately it follows (Exo 4:20), he took his wife, and his sons, and set out for Egypt. Note, Though corruption may object much against the services God calls us to, yet grace will get the upper hand, and will be obedient to the heavenly vision.