Exodus 4:15-17
4:15 “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.
4:16 He will speak for you to the people, and it will be as if he were your mouth and as if you were his God.
4:17 You will also take in your hand this staff, with which you will do the signs.”