1 Samuel 20:16

So Jonathan made a covenant with the house of David ,.... Not with David himself only, which was now renewed, but with his family also:

saying , let the Lord even require it at the hand of David's enemies ; take vengeance on Jonathan, or on any of his posterity, should they break this covenant, by showing themselves enemies to David, and his crown; and, on the other hand, also on David, and his posterity, should they not show kindness to Jonathan and his seed, according to the tenor of this covenant.