Source: Exodus 3-7:6
After Moses fled Egypt, he settled in Midian and married a woman named Zipporah. They had a son named Gershom, and Moses tended the sheep owned by his father-in-law Jethro. One day Moses had led the sheep to the mountain of God, Horeb (also known as Mt. Sinai). There at Horeb, the angel of the Lord appeared to Moses in a flame of fire coming from a bush. Though the bush was on fire, it was not burned up, and Moses came closer to see this amazing sight. As Moses turned aside to see the burning bush, God called out to Moses. "Moses, Moses", God said, and Moses replied "Here am I". God told Moses to not come any closer until Moses had taken off his shoes, for the ground Moses stood on was holy ground. God then said, "I am the God of thy father, the God of Abraham, the God of Isaac, and the God of Jacob". Moses hid his face, because he was afraid to look at God.
The Lord told Moses that He knew that the Israelites were suffering at the hands of Pharaoh and the Egyptians, and that God was now going to deliver them from Egypt, and lead Israel to a "land flowing with milk and honey". This land was Canaan, the land that God had promised to Abraham, Isaac, and Jacob many years before. God then told Moses that He was sending Moses to lead the Israelites out of Egypt. Moses tried to argue with God, telling Him that he was not the right man for this important job. But God reassured Moses, telling him that He would certainly be with Moses. Moses feared that the Israelites would not believe him, so God showed Moses several miraculous signs that he could show the Israelites if they did not believe him. However, Moses was still unsure of himself, telling God that he was not a good speaker. God told Moses that He could certainly make Moses speak well, but Moses was not convinced. Finally, God told Moses that he would tell Aaron, Moses brother, to speak for Moses.
Moses got Jethro's approval to leave, and he departed for Egypt with his wife and sons. As God promised, He told Aaron to go into the wilderness to meet Moses. Aaron departed into the wilderness and met Moses at the mount of God. Moses told Aaron what God had said and also the signs that God had showed Moses. Moses and Aaron went to the elders of Israel and Aaron told them of God's words and signs to Moses. The people believed Aaron's words and bowed their heads and worshipped God.
After meeting the elders of Israel, Moses and Aaron went to see Pharaoh. They told Pharaoh that the Lord God commanded him to let the Israelites leave Egypt. Pharaoh was unimpressed, and asked "Who is the Lord, that I should obey his voice to let Israel go? I know not the Lord, neither will I let Israel go". Pharaoh then added more work to the Israelites, telling them to find their own straw for the bricks that they made as Pharaoh's slaves. However, the Israelites still had to make the same number of bricks each day. It was impossible for the Israelites to find the straw and still make the usual number of bricks each day. The Israelites blamed Moses and Aaron for this bad turn of events, and Moses was disheartened. He asked God why these things had happened. Not only had he failed to deliver the Israelites from Egypt, things had actually gotten worse for them.
God then spoke to Moses, telling him and the Israelites to not get discouraged, that the Lord God was about to show Pharaoh and the Egyptians His might and power. God had not forgotten His promises to the Israelites, and that soon God would lead Israel out of Egypt to the land He had promised Abraham, Isaac, and Jacob. Moses still had doubts, but God told him that God would soon work signs and wonders in Egypt. Pharaoh would not hearken to these miracles, but in the end God would lead Israel out anyway. Moses and Aaron obeyed, and went to see Pharaoh again.