1 Samuel 20:14-18

And thou shalt not only while yet I live shew me the kindness of the LORD, that I die not:

But also thou shalt not cut off thy kindness from my house for ever: no, not when the LORD hath cut off the enemies of David every one from the face of the earth.

So Jonathan made a covenant with the house of David, saying, Let the LORD even require it at the hand of David’s enemies.

And Jonathan caused David to swear again, because he loved him: for he loved him as he loved his own soul.

Then Jonathan said to David, To morrow is the new moon: and thou shalt be missed, because thy seat will be empty.