'Oath' in the Bible

May God's punishment be on Abner, if I do not for David as the Lord in his oath has said,

And the people came to make David take food, while it was still day, but David with an oath said, May God's punishment be on me if I take a taste of bread or any other thing till the sun has gone down!

Now at the end of four years, Absalom said to the king, Let me go to Hebron and give effect to the oath which I made to the Lord:

For while I was living in Geshur in Aram, your servant made an oath, saying, If ever the Lord lets me come back to Jerusalem, I will give him worship in Hebron.

So get up now, and go out and say some kind words to your servants; for, by the Lord, I give you my oath, that if you do not go out, not one of them will keep with you tonight; and that will be worse for you than all the evil which has overtaken you from your earliest years.

So the king said to Shimei, You will not be put to death. And the king gave him his oath.

Then the king sent for the Gibeonites; (now the Gibeonites were not of the children of Israel, but were the last of the Amorites, to whom the children of Israel had given an oath; but Saul, in his passion for the children of Israel and Judah, had made an attempt on their lives:)

But the king did not give up Mephibosheth, the son of Saul's son Jonathan, because of the Lord's oath made between David and Jonathan, the son of Saul.

But Abishai, the son of Zeruiah, came to his help, and, turning on the Philistine, gave him his death-blow. Then David's men took an oath, and said, Never again are you to go out with us to the fight, so that you may not put out the light of Israel.