Exodus 4:14-16

14Then the Lord became angry with Moses. He said, ‘Aaron, the Levite, is your brother. I know that he can speak very well. Look! He is coming to meet you now. When he sees you, he will be very happy.

15So this is what you must do. You must speak to him. You must tell him what to say. I will help both of you to speak. And I will teach both of you what you must do.

16Aaron will speak to the people on your behalf. He will be like your mouth, to speak your message. And you will be like God to him. You will tell him what to say.