when someone told me, ‘Look, Saul is dead,’ and thought he was a bearer of good news, I seized him and put him to death at Ziklag. That was his reward for his news!
He recalls killing the man who brought Saul's death as supposed good news, calling that death his reward.
It provides the precedent for how David treats such reports.
9But David answered Rechab and his brother Baanah, the sons of Rimmon the Beerothite, “As surely as the LORD lives, who has redeemed my life from all distress, 10when someone told me, ‘Look, Saul is dead,’ and thought he was a bearer of good news, I seized him and put him to death at Ziklag. That was his reward for his news! 11How much more, when wicked men kill a righteous man in his own house and on his own bed, shall I not now require his blood from your hands and remove you from the earth!” 12So David commanded his young men, and they killed Rechab and Baanah. They cut off their hands and feet and hung their bodies by the pool in Hebron, but they took the head of Ish-bosheth and buried it in Abner’s tomb in Hebron.