1 Samuel 20:16-17, 42

And Jonathan made a covenant with the house of David, saying, “May the LORD take vengeance on David’s enemies.” And Jonathan made David swear again by his love for him, for he loved him as he loved his own soul.

Then Jonathan said to David, “Go in peace, because we have sworn both of us in the name of the LORD, saying, ‘The LORD shall be between me and you, and between my offspring and your offspring, forever.’” And he rose and departed, and Jonathan went into the city.