You're probably talking about Moses?

From Exodus chapter 4 you read about how Moses didn't want to accept his assignment "Moses said to the Lord, “Pardon your servant, Lord. I have never been eloquent, neither in the past nor since you have spoken to your servant. I am slow of speech and tongue.”

The Lord said to him, “Who gave human beings their mouths? Who makes them deaf or mute? Who gives them sight or makes them blind? Is it not I, the Lord? Now go; I will help you speak and will teach you what to say.”

But Moses said, “Pardon your servant, Lord. Please send someone else.”

Is that what you were looking for OP?