The promise here is introduced with solemnity: "As for me," says the great God, "behold, behold and admire it, behold and be assured of it, my covenant is with thee;" as before (v. 2), I will make my covenant. Note, The covenant of grace is a covenant of God's own making; this he glories in (as for me), and so may we. Now here,
I. It is promised to Abraham that he should be a father of many nations; that is, 1. That his seed after the flesh should be very numerous, both in Isaac and Ishmael, as well as in the sons of Keturah: something extraordinary is doubtless included in this promise, and we may suppose that the event answered to it, and that there have been, and are, more of the children of men descended from Abraham than from any one man at an equal distance with him from Noah, the common root. 2. That all believers in every age should be looked upon as his spiritual seed, and that he should be called, not only the friend of God, but the father of the faithful. In this sense the apostle directs us to understand this promise, Rom. iv. 16, 17. He is the father of those in every nation that by faith enter into covenant with God, and (as the Jewish writers express it) are gathered under the wings of the divine Majesty.
II. In token of this his name was changed from Abram, a high father, to Abraham, the father of a multitude. This was, 1. To put an honour upon him. It is spoken of as the glory of the church that she shall be called by a new name, which the mouth of the Lord shall name, Isa. lxii. 2. Princes dignify their favourites by conferring new titles upon them; thus was Abraham dignified by him that is indeed the fountain of honour. All believers have a new name, Rev. ii. 17. Some think it added to the honour of Abraham's new name that a letter of the name Jehovah was inserted into it, as it was a disgrace to Jeconiah to have the first syllable of his name cut off, because it was the same as the first syllable of the sacred name, Jer. xxii. 28. Believers are named from Christ, Eph. iii. 15. 2. To encourage and confirm the faith of Abraham. While he was childless perhaps even his own name was sometimes an occasion of grief to him: why should he be called a high father who was not a father at all? But now that God had promised him a numerous issue, and had given him a name which signified so much, that name was his joy. Note, God calls things that are not as though they were. It is the apostle's observation upon this very thing, Rom. iv. 17. He called Abraham the father of a multitude because he should prove to be so in due time, though as yet he had but one child.