Exodus 3:11-14

And Moses said to God, Who am I, that I should go to Pharaoh and bring the Israelites out of Egypt? God said, I will surely be with you; and this shall be the sign to you that I have sent you: when you have brought the people out of Egypt, you shall serve God on this mountain [Horeb, or Sinai]. And Moses said to God, Behold, when I come to the Israelites and say to them, The God of your fathers has sent me to you, and they say to me, What is His name? What shall I say to them? And God said to Moses, I AM WHO I AM and WHAT I AM, and I WILL BE WHAT I WILL BE; and He said, You shall say this to the Israelites: I AM has sent me to you!