“But Moses said to Yahweh, ‘Oh, my Yahweh, I have never been eloquent, neither in the past nor even now that you have spoken to your servant. But I am slow of speech and of tongue.’ Then Yahweh said to him, ‘Who gives speech to morals? Who makes them mute or deaf, seeing or blind? Is it not I, Yahweh? Now go, and I will be with your mouth and teach you what you are to speak.’ But he said, ‘Oh, my Yahweh, send someone else.’ Then the anger of Yahweh was kindled against Moses and he said, ‘What of your brother Aaron the Levite? I know that he can speak fluently, and even now he is coming out to meet you, and when he sees you his heart will be glad. You shall speak to him and put the words in his mouth. I will be with your mouth and with his mouth, and will teach you what you shall do. He indeed shall speak for you to the people. He shall serve as a mouth for you, and you shall serve as God for him. Take in your hand this staff, with which you shall perform the signs.’”
Moses also complained that he was not eloquent or a good speaker. He was slow of speech and tongue. However, Yahweh replied that he would be the mouth of Moses and teach him what to say. Still Moses pleaded to send someone else. Then Yahweh got angry. They finally decided that Aaron, the Levite brother of Moses, could speak fluently. Aaron enters here. There was no mention of a brother of Moses before this since there is so little about the childhood of Moses. It is not clear where he came from. So here is the arrangement. God would be in both their mouths and teach Moses what to do. Aaron would speak for Moses to the people. He would be the mouth of Moses and Moses would be like God for him. Thus it is not unusual to think of Moses as God, since he also brought his staff to perform the miraculous signs.