'O God' in the Bible

He shall not make himself unclean for his father or for his mother, for his brother or for his sister, when they die, because his separation to God is on his head.

Moses cried out to the Lord, saying, “O God, heal her, I pray!”

But they fell on their faces and said, “O God, God of the spirits of all flesh, when one man sins, will You be angry with the entire congregation?”

Balaam said to God, “Balak the son of Zippor, king of Moab, has sent word to me,