2 Samuel 21:10-14. Now that David is king, after Saul's death, the Gibeonites ask David for the lives of seven of Saul's sons in retribution for Saul's campaign against them. David hands over two of Saul's sons by Rizpah, and five of Saul's daughters sons, all of whom are hanged by the Gibeonites. In her grief, Rizpah goes to the place where the bodies lay and stays there, not allowing the birds or beasts to get to them. When David hears of his actions, he goes to the men who had stolen Saul's and Jonathan's bones (which had been in a public square pror to being stolen) and gets them back; he also gathers up the bones of the hanged men, and he buries all of them in the land of Benjamin, in the tomb of Kish, Saul's father. "And after that God heeded supplications for the land." 

Rizpah's actions and grief remind David that these men, though his enemies, are to be treated with respect. Although David had reason to punish them, as did the Gideonites, Rizpah loved them. We are all loved and we all deserve respect as children of God, even in our death. Rizpah's love and grief cause her to sacrifice for the bodies of her dead. To David's credit, this was enough to wake him up to  wrongness of leaving Saul, Jonathan, and the seven hanged men unburied. He seeks out Saul and Jonathan's bodies, gathers up the others, and gives them all a proper burial in their homeland. This is good and right and so, from that day, God heeded supplications for the land.

We are always to love our enemies, but we all know it is not always easy. When they are dead it is so easy to leave their fate in God's hands and forget about them. They are no longer bothering us, so why should we worry about them? But God never forgets his children, so our duty is to remember our enemies even in death and always treat them with respect. This includes a proper burial, and is why buring the dead is one of the Corporal works of Mercy.