He (Moses) said, "Oh, Master, please! Send somebody else!"I can relate to Moses in his reluctance and fear. God was pushing him to take a risk. It is much easier to see and accept miracles around you or in someone else than to believe God can do the same in your own life. Moses had a fear of public speaking and even though God assured him that he would give him the strength and ability that was needed, Moses resisted. Even after direct contact with God and immediate physical miracles or signs Moses couldn't get past his fear.
God got angry with Moses: "Don't you have a brother, Aaron the Levite? He's good with words, I know he is. He speaks very well. In fact, at this very moment he's on his way to meet you. When he sees you he's going to be glad. You'll speak to him and tell him what to say. I'll be right there with you as you speak and with him as he speaks, teaching you step by step. He will speak to the people for you. He'll act as your mouth, but you'll decide what comes out of it. Now take this staff in your hand; you'll use it to do the signs." (The Message Version)
We see the grace and mercy of God even in his anger. God is patient with Moses. He doesn't move on to someone else with more faith instead he creates a way to push Moses beyond his fear, just enough that he will take on the mission. God teams him up with another person, his brother, to boost his confidence, and help him. Moses will soon realize that God will provide him with the ability needed.