Exodus 4:15 - Exposition

Thou shalt speak unto him and put words in his mouth . Moses was to tell Aaron what to say—furnish, i.e ; the matter of his speeches—and Aaron was to clothe this matter in fitting words. God promised to be with both of their mouths; with Moses', to make him give right directions to Aaron; with Aaron's, to make him utter them persuasively: Moses' position was still the more honourable one, though Aaron's might seem the higher to the people.