'O God' in the Bible

So God gave Daniel favour and grace before the chief chamberlain,

Therefore I will and command, that all people, kindreds and tongues, which speak any blasphemy against the God of Shadrach, Meshach, and Abednego, shall die and their houses shall be prised: Because, there is no God that may save, as this."

and I turned me unto God the LORD, for to pray and make mine intercession, with fasting, sack cloth and ashes.

The wise, such as have taught others, shall glister as the shining of heaven: and those that have instructed the multitude unto Godliness, shall be as the stars, world without end.