And David said unto him, How wast thou not afraid to stretch forth thine hand to destroy the LORD’s anointed?
Saul was the Lord's anointed, consecrated by God to rule Israel, and David treated him as such even after his death. To lift a hand to destroy that anointed king was a grave crime to be feared, so David's question rebuked the Amalekite for showing no such fear in claiming the deed. The man's own mouth testified against him that he had struck Saul down, and that self-accusation brought the death penalty upon him.
Saul was the Lord's anointed, consecrated by God to rule Israel, and David treated him as such even after his death. To lift a hand to destroy that anointed king was a grave crime to be feared, so David's question rebuked the Amalekite for showing no such fear in claiming the deed. The man's own mouth testified against him that he had struck Saul down, and that self-accusation brought the death penalty upon him.