“'So now, go. I am sending you to Pharaoh to bring my people the Israelites out of Egypt.' But Moses said to God, ‘Who am I that I should go to Pharaoh and bring the Israelites out of Egypt?’ And God said, ‘I will be with you. And this will be the sign to you that it is I who have sent you: When you have brought the people out of Egypt, you will worship God on this mountain.’ Moses said to God, ‘Suppose I go to the Israelites and say to them, ‘The God of your fathers has sent me to you,’ and they ask me, ‘What is his name?’ Then what shall I tell them?’ God said to Moses, 'I am who I am. This is what you are to say to the Israelites: ‘I am has sent me to you.’”  Exodus 3:10-14 (NIV)

"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.’”  Exodus 4:10-13 (NIV)

“But he said to me, ‘My grace is sufficient for you, for my power is made perfect in weakness.’ Therefore I will boast all the more gladly of my weaknesses, so that the power of Christ may rest upon me.”  2 Corinthians 12:9 (ESV)