Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) came out and said: "No sin is too great for Allah, the Mighty and Majestic, to forgive. Among the people before you there was a man who killed ninety-eight people. Then he came to a monk and said: I have killed ninety-eight people; is there any room for repentance for me? The monk said: You have gone beyond all bounds. So he went towards him and killed him too. Then he came to a second monk and said: I have killed ninety-nine people; is there any room for repentance for me? He said: No, you have gone beyond all bounds. So he went towards him and killed him too. Then he came to yet another monk and said: I have killed a hundred people; is there any room for repentance for me? He said: You have certainly gone beyond all bounds, and I do not know; but here there are two towns, one called Nadrah and the other called Kafrah. The people of Nadrah do the deeds of the people of Paradise, and no one other than them stays there; and the people of Kafrah do the deeds of the people of Hell, and no one other than them stays there. So go to Nadrah; if you stay there and do deeds like theirs, there is no doubt about your repentance. So he set out towards Nadrah, until, when he was between the two towns, death overtook him. The angels asked their Lord about him, and Allah said: See to which of the two towns he was nearer, and count him among its people. They found him nearer to Nadrah by the length of a fingertip, so he was recorded among its people."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13673