'O God' in the Bible

In the second year of their coming to God’s house at Jerusalem, in the second month, Zerubbabel the son of Shealtiel and Jeshua the son of Jozadak began [the work], with the rest of their brothers—the priests and Levites and all who came to Jerusalem from the captivity. They appointed the Levites, from twenty years old and upward, to oversee the work of the house of the Lord.

and set the priests in their courses, and the Levites in their offices to minister unto God which is at Jerusalem as it is written in the book of Moses.

And you, Ezra, according to God’s wisdom that you possess, appoint magistrates and judges to judge all the people in the region west of the Euphrates who know the laws of your God and to teach anyone who does not know them.

And after everything which has come on us because of our evil-doing and our great sin, and seeing that the punishment which you, O God, have given us, is less than the measure of our sins, and that you have kept from death those of us who are here;

Anyone who did not come within three days, by decision of the officials and elders, all of his possessions would be devoted to God, and he himself would be excluded from the assembly of exiles.