'O God' in the Bible

And they were helped against them, and the Hagarites were delivered into their hand, and all that were with them: for they cried to God in the battle, and he was entreated by them; because they put their trust in him.

And say ye, Save us, O God of our salvation, and gather us together, and deliver us from the heathen, that we may give thanks to thy holy name, and glory in thy praise.

And yet this was a small thing in thy eyes, O God; for thou hast also spoken of thy servant's house for a great while to come, and hast regarded me according to the estate of a man of high degree, O LORD God.

And David said to God, I have sinned greatly, because I have done this thing: but now, I beseech thee, do away the iniquity of thy servant; for I have done very foolishly.

And David said to God, Is it not I that commanded the people to be numbered? even I it is that have sinned and done evil indeed; but as for these sheep, what have they done? let thy hand, I pray thee, O LORD my God, be on me, and on my father's house; but not on thy people, that they should be afflicted.

And his brethren, men of valor, were two thousand and seven hundred chief fathers, whom king David made rulers over the Reubenites, the Gadites, and the half-tribe of Manasseh, for every matter pertaining to God, and affairs of the king.