Exodus 4:10-12 ESV
But Moses said to the LORD, Oh, my Lord, I am not eloquent, either in the past or since you have spoken to your servant, but I am slow of speech and of tongue.
Then the LORD said to him, Who has made man's mouth? Who makes him mute, or deaf, or seeing, or blind? Is it not I, the LORD?
Now therefore go, and I will be with your mouth and teach you what you shall speak.