1 Samuel 20:16-17, 42

So Jonathan made a covenant with the house of David. [He added,] “May the LORD require it at the hands of David’s enemies. [that is, hold them accountable for any harm they inflict on David].” Jonathan made David vow again because of his love for him, for Jonathan loved him as himself.

Jonathan told David, “Go in safety, inasmuch as we have sworn to each other in the name of the LORD, saying, ‘The LORD shall be between me and you, and between my descendants and yours forever.’ ” Then he stood and left, while Jonathan went into the city.