Exodus 3:11-15 (NKJV)

11 But Moses said to God, “Who am I that I should go to Pharaoh, and that I should bring the children of Israel out of Egypt?”

12 So He said, “I will certainly be with you. And this shall be a sign to you that I have sent you: When you have brought the people out of Egypt, you shall serve God on this mountain.”

13 Then Moses said to God, “Indeed, when I come to the children of Israel 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?”

14 And God said to Moses, “I AM WHO I AM.” And He said, “Thus you shall say to the children of Israel, ‘I AM has sent me to you.’ ” 

15 Moreover God said to Moses, “Thus you shall say to the children of Israel: ‘The Lord God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me to you. This is My name forever, and this is My memorial to all generations.’