Exodus 3:11-13

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?” And God said, “Certainly I will be with you, and this shall be the sign to you that it is I who have sent you: when you have brought the people out of Egypt, you shall serve and worship God at this mountain.” Then Moses said to God, “Behold, when I come to the Israelites and say to them, ‘The God of your fathers (ancestors) has sent me to you,’ and they say to me, ‘What is His name?’ What shall I say to them?”