'Oath' in the Bible

The Lord said, "I have made a covenant with my chosen one; I have made a promise on oath to David, my servant:

Where are your earlier faithful deeds, O Lord, the ones performed in accordance with your reliable oath to David?

the promise he made to Abraham, the promise he made by oath to Isaac!

The Lord makes this promise on oath and will not revoke it: "You are an eternal priest after the pattern of Melchizedek."

and how he made a vow to the Lord, and swore an oath to the powerful ruler of Jacob.