Yes, the Bible indicates that Moses had a speech impairment, which caused him to fear the mission that God gave him. In the book of Exodus (4:10), just after Moses has been called by God and told to go to the pharaoh and lead the Israelites out of Egypt, he appeals to the Lord, saying, “If you please, Lord, I have never been eloquent … I am slow of speech and tongue,” and, later (4:13), “If you please, Lord, send someone else.” God reassures Moses and instructs him to go meet his brother, Aaron the Levite, who is eloquent and will speak to the people for Moses.