Exodus 3:11
And Moses said to God, Who am I, that I should go to Pharaoh, and that I should bring forth the children of Israel out of Egypt?
Torrey's Topical Textbook—AKJV

Exodus 4:10
And Moses said to the LORD, O my LORD, I am not eloquent, neither heretofore, nor since you have spoken to your servant: but I am slow of speech, and of a slow tongue.
Torrey's Topical Textbook—AKJV