Joh 8:58  Jesus said unto them, Verily, verily, I say unto you, Before Abraham was, I am.

John 8:58  Jesus said unto them, verily, verily, I say unto you,…. Whether it will be believed or not, it is certainly fact:

before Abraham was, I am; which is to be understood, not of his being in the purpose and decree of God, foreordained to sufferings, and to glory; for so all the elect of God may be said to be before Abraham, being chosen in Christ before the foundation of the world: or that Christ was man, before Abraham became the father of many nations; that is, before the calling of the Gentiles; for nothing is said in the text about his being the father of many nations; it is a bold and impudent addition to it: and besides, Abraham was made the father of many nations, as Ishmaelites, Israelites, Hagarenes, &c. long before the incarnation of Christ; yea, he was so from the very promise in Gen_17:5, which so runs, “a father of many nations have I made thee”; so that this appears a false sense of the text, which is to be understood of the deity, eternity, and immutability of Christ, and refers to the passage in Exo_3:14. “I am that I am-I am hath sent me unto you”, the true Jehovah; and so Christ was before Abraham was in being, the everlasting I am, the eternal God, which is, and was, and is to come: he appeared in an human form to our first parents before Abraham was, and was manifested as the Mediator, Saviour, and living Redeemer, to whom all the patriarchs before Abraham looked, and by whom they were saved: he was concerned in the creation of all things out of nothing, as the efficient cause thereof; he was set up from everlasting as Mediator; and the covenant of grace was made with him, and the blessings and promises of it were put into his hands before the world began; the eternal election of men to everlasting life was made in him before the foundation of the world; and he had a glory with his Father before the world was; yea, from all eternity he was the Son of God, of the same nature with him, and equal to him; and his being of the same nature proves his eternity, as well as deity, that he is from everlasting to everlasting God; and is what he ever was, and will be what he now is: he is immutable, the same today, yesterday, and for ever; in his nature, love, grace, and fulness, he is the invariable and unchangeable I am.

Reference

Gill’s exposition of the entire bible