Exodus 4:14-17

14Then the Lord became angry with Moses, and he said, “What about your brother Aaron the Levite? I know that he can speak very well. Moreover, he is coming to meet you, and when he sees you he will be glad in his heart.

15“So you are to speak to him and put the words in his mouth. And as for me, I will be with your mouth and with his mouth, and I will teach you both what you must do.

16He will speak for you to the people, and it will be as if he were your mouth and as if you were his God.

17You will also take in your hand this staff, with which you will do the signs.”