My firstborn - The expression would be perfectly intelligible to Pharaoh, whose official designation was "son of Ra." In numberless inscriptions the Pharaohs are styled "own sons" or "beloved sons" of the deity. It is here applied for the first time to Israel; and as we learn from Exodus 4:23, emphatically in antithesis to Pharaoh's own firstborn.

Israel is my son, even my firstborn - That is, The Hebrew people are unutterably dear to me.

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 firstborn is, or as his only son: adoption is one of the privileges peculiar to Israel after the flesh, even national adoption, with all the external privileges appertaining to it, Romans 9:4.

In order that Pharaoh might form a true estimate of the solemnity of the divine command, Moses was to make known to him not only the relation of Jehovah to Israel, but also the judgment to which he would be exposed if he refused to let Israel go. The relation in which Israel stood to Jehovah was expressed by God in the words, "Israel is My first-born son." Israel was Jehovah's son by virtue of his election to be the people of possession (Deuteronomy 14:1-2). This election began with the call of Abraham to be the father of the nation in which all the families of the earth were to be blessed. On the ground of this promise, which was now to be realized in the seed of Abraham by the deliverance of Israel out of Egypt, the nation of Israel is already called Jehovah's "son," although it was through the conclusion of the covenant at Sinai that it was first exalted to be the people of Jehovah's possession out of all the nations (Exodus 19:5-6). The divine sonship of Israel was therefore spiritual in its nature: it neither sprang from the fact that God, as the Creator of all nations, was also the Creator, or Begetter, and Father of Israel, nor was it founded, as Baumgarten supposes, upon "the physical generation of Isaac, as having its origin, not in the power of nature, but in the power of grace." The relation of God, as Creator, to man His creature, is never referred to in the Old Testament as that of a father to a son; to say nothing of the fact that the Creator of man is Elohim, and not Jehovah. Wherever Jehovah is called the Father, Begetter, or Creator of Israel (even in Deuteronomy 32:18; Jeremiah 2:27; Isaiah 44:8; Malachi 1:6 and Malachi 2:10), the fatherhood of God relates to the election of Israel as Jehovah's people of possession. But the election upon which the υἱοθεσία of Israel was founded, is not presented in the aspect of a "begetting through the Spirit;" it is spoken of rather as acquiring or buying (קנה), making (עשׂה), founding or establishing (כּנן, Deuteronomy 32:6). Even the expressions, "the Rock that begat thee," "God that bare thee" (Deuteronomy 32:18), do not point to the idea of spiritual generation, but are to be understood as referring to the creation; just as in Psalm 90:2, where Moses speaks of the mountains as "brought forth" and the earth as "born." The choosing of Israel as the son of God was an adoption flowing from the free grace of God which involved the loving, fatherly treatment of the son, and demanded obedience, reverence, and confidence towards the Father (Malachi 1:6). It was this which constituted the very essence of the covenant made by Jehovah with Israel, that He treated it with mercy and love (Hosea 11:1; Jeremiah 31:9, Jeremiah 31:20), pitied it as a father pitieth his children (Psalm 103:13), chastened it on account of its sins, yet did not withdraw His mercy from it (2 Samuel 7:14-15; Psalm 89:31-35), and trained His son to be a holy nation by the love and severity of paternal discipline. - Still Israel was not only a son, but the "first-born son" of Jehovah. In this title the calling of the heathen is implied. Israel was not to be Jehovah's only son, but simply the first-born, who was peculiarly dear to his Father, and had certain privileges above the rest. Jehovah was about to exalt Israel above all the nations of the earth (Deuteronomy 28:1). Now, if Pharaoh would not let Jehovah's first-born son depart, he would pay the penalty in the life of his own first-born (cf. Exodus 12:29). In this intense earnestness of the divine command, Moses had a strong support to his faith. If Israel was Jehovah's first-born son, Jehovah could not relinquish him, but must deliver His son from the bondage of Egypt.

And thou shalt say unto Pharaoh, Thus saith the LORD, Israel is my son, even my {k} firstborn:

(k) Meaning, most dear to him.

4:22 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: Israel is my son, my first - born - Precious in my sight, honourable, and dear to me.

4:18-23 After God had appeared in the bush, he often spake to Moses. Pharaoh had hardened his own heart against the groans and cries of the oppressed Israelites; and now God, in the way of righteous judgment, hardens his heart against the teaching of the miracles, and the terror of the plagues. But whether Pharaoh will hear, or whether he will forbear, Moses must tell him, Thus saith the Lord. He must demand a discharge for Israel, Let my son go; not only my servant, whom thou hast no right to detain, but my son. It is my son that serves me, and therefore must be spared, must be pleaded for. In case of refusal I will slay thy son, even thy first-born. As men deal with God's people, let them expect so to be dealt with.