Exodus 4:14-17

Then the anger of the LORD burned against Moses, and He said, “Is there not your brother Aaron the Levite? I know that he speaks fluently. And moreover, behold, he is coming out to meet you; when he sees you, he will be glad in his heart. You are to speak to him and put the words in his mouth; and I, even I, will be with your mouth and his mouth, and I will teach you what you are to do. Moreover, he shall speak for you to the people; and he will be as a mouth for you and you will be as God to him. You shall take in your hand this staff, with which you shall perform the signs.”