Matthew Henry Commentary Exodus 3:11-15

"And Moses said unto God, Who am I, that I should go unto Pharaoh, and that I should bring forth the children of Israel out of Egypt? And he said, Certainly I will be with thee; and this shall be the token unto thee, that I have sent thee: when thou hast brought forth the people out of Egypt, ye shall serve God upon this mountain. And Moses said unto God, Behold, when I come unto the children of Israel, and shall say unto them, The God of your fathers hath sent me unto you; and they shall say to me, What is his name? What shall I say unto them? And God said unto Moses, I AM THAT I AM: and he said, Thus shalt thou say unto the children of Israel, I AM hath sent me unto you. And God said moreover unto Moses, Thus shalt thou say unto the children of Israel, Jehovah, the God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, hath sent me unto you: this is my name forever, and this is my memorial unto all generations." — Exodus 3:11-15 (ASV)

Previously, Moses thought he was able to deliver Israel and set about the work too hastily. Now, though he is the fittest person on earth for it, he knows his own weakness. This was the effect of more knowledge of God and of himself. Previously, self-confidence mingled with strong faith and great zeal; now, sinful distrust of God crept in under the guise of humility; so defective are the strongest graces and the best duties of even the most eminent saints.

But all objections are answered by the words, Certainly I will be with thee. That is enough. God would now be known by two names. One name denotes what he is in himself: I AM THAT I AM. This explains his name Jehovah and signifies:

1. That he is self-existent: he has his being from himself.
2. That he is eternal and unchangeable, and always the same, yesterday, today, and forever.
3. That he is incomprehensible; we cannot find him out by searching. This name checks all bold and curious inquiries concerning God.
4. That he is faithful and true to all his promises, unchangeable in his word as well as in his nature; let Israel know this: I AM hath sent me unto you. I am, and there is none else besides me. All else have their being from God and are wholly dependent upon him.

Also, there is a name that denotes what God is to his people. The LORD God of your fathers sent me unto you. Moses must revive among them the religion of their fathers, which was almost lost; and then they might expect the speedy fulfillment of the promises made to their fathers.