1 Samuel 20:16-17, 42

So Jonathan made a covenant with the house of David, saying, And Jehovah will require it at the hand of David’s enemies. And Jonathan caused David to swear again, for the love that he had to him; for he loved him as he loved his own soul.

And Jonathan said to David, Go in peace, forasmuch as we have sworn both of us in the name of Jehovah, saying, Jehovah shall be between me and thee, and between my seed and thy seed, for ever. And he arose and departed: and Jonathan went into the city.