Exodus 4:16

And he shall be thy spokesman unto the people; and he shall be, even he shall be to thee instead of a mouth, and thou shalt be to him instead of God, to make known to him both the form and the contents of his speeches to the people. As Moses, the prophet, speaks only what God commands him to say, thus Aaron was to defer to Moses in stating only what Moses told him. "He that has the Word of God and is a believer has the Spirit and the power of God, also divine wisdom, truth, heart, mind, and disposition, and everything that pertains to God. " (Luther.)