'O God' in the Bible

Then shalt thou pass on quickly from thence onwards, and come as far as the oak of Tabor, and there shall find thee there, three men going up unto God, at Bethel, - one, carrying three kids, and, another, carrying three cakes of bread, and, another, carrying a skin of wine;

Then said Saul - Let us go down after the Philistines by night, and make of them a prey until the morning light, and let us not leave of them, a man. And they said, All that is good in thine eyes, do! Then said the priest, Let us draw near hither unto God.

And Saul said unto Yahweh - O God of Israel! now set forth the truth. Then were, Jonathan and Saul, taken, and, the people, escaped.