Mukhtasar Bukhari

Narrated from Abu Huraira (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Allah will smile at two men, one of whom killed the other, yet both will enter Paradise. One fought in the way of Allah and was martyred. Then Allah granted the killer the ability to repent (he became a Muslim), and he too was martyred (in the way of Allah)."

´Sayyiduna Abu Hurairah (may Allah be pleased with him) says that` I went to the Messenger of Allah (peace and blessings of Allah be upon him). At that time, he (peace be upon him) was in Khaybar. The Muslims had conquered Khaybar. I submitted, "O Messenger of Allah! (In the spoils of war) allot my share as well." Then one of the sons of Sa'id bin 'As said, "O Messenger of Allah! Do not allot his share." I said, "O Messenger of Allah! He is the killer of Ibn Qawqal (may Allah be pleased with him)." So the son of Sa'id bin 'As said, "How strange! (Abu Hurairah) who has come to us from the direction of Dhan (the name of a mountain) accuses me of killing a Muslim, whom Allah honored at my hands (i.e., with martyrdom) and did not disgrace me at his hands (i.e., by being killed and becoming a wretched corpse of Hellfire)."