To Moses’ second misgiving God made a promise of exceeding beauty, which all who speak for God should consider. Compare Exo 4:12 with Jer 1:7-9 and 1Co 2:4. If we looked at our natural powers as Paul used to do, we should glory in our lack of eloquence, as affording a better platform on which God might work. See 2Co 12:9-10.
In answer to the third misgiving God gave him his brother as assistant. Indeed, he was already on his way; but he was a weak man, and gave to Moses a great amount of anxiety and pain in their afterlife. After all, it is best for a man to lean only on God for counsel and ready help. If we step forth with this supreme alliance, we shall escape the hampering association with Aarons. We may as well get all we need at first-hand.