2 Samuel 4:11
How much more, when wicked men have slain a righteous person in his own house upon his bed? shall I not therefore now require his blood of your hand, and take you away from the earth? How much more, when wicked men have slain a righteous person in his own house upon his bed? shall I not therefore now require his blood of your hand, and take you away from the earth?
The righteous man struck down in his own house upon his bed was Ishbosheth of Saul's house, counted righteous not for his cause but as an innocent victim cut off at home while lying helpless in bed. The wicked men were his murderers, who came to David claiming their crime served him and that God had avenged him upon Saul's line, but David utterly rejected their plea and refused to accept the killing as done for him or by divine warrant. To require his blood of their hand and take them away from the earth was to hold them personally accountable for murder and to have them put to death for it.