'Oath' in the Bible

So then, because he was a prophet and knew that God had sworn to him with an oath to seat one of his descendants on his throne,

When morning came, the Jews formed a conspiracy and bound themselves with an oath not to eat or drink anything until they had killed Paul.

They went to the chief priests and the elders and said, "We have bound ourselves with a solemn oath not to partake of anything until we have killed Paul.

So do not let them persuade you to do this, because more than forty of them are lying in ambush for him. They have bound themselves with an oath not to eat or drink anything until they have killed him, and now they are ready, waiting for you to agree to their request."