But Moses said to God, “Who am I that I should go to Pharaoh, and bring the Israelites out of Egypt?” He said, “I will be with you; and this shall be the sign for you that it is I who sent you: when you have brought the people out of Egypt, you shall worship God on this mountain.”
Haha. God pretty much says, “this will be the sign that I am right. When everything I’m saying ends up happening”. And so Moses’ assurance in the moment is a promise for the future.