'O God' in the Bible

And it happened after many days the king of Egypt died. And the sons of Israel sighed because of the bondage, and they cried, and their cry came up to God because of the bondage.

And Moses said to God, Who am I that I should go to Pharaoh, and that I should bring forth the sons of Israel out of Egypt?

And Moses said to God, Behold, when I come to the sons of Israel, and shall say to them, The God of your fathers has sent me to you, and they shall say to me, What is His name? What shall I say to them?

Listen now to my voice; I will give you counsel, and God will be with you. You be for the people toward God, that you may bring the causes to God.

And Moses went up to God, and Jehovah called to him out of the mountain, saying, You shall say to the house of Jacob, and tell the sons of Israel: