Abu Huraira reported God's Messenger as saying, "God most high will cheerfully welcome two men one of whom kills the other. They will enter paradise, one having fought in God’s path and been killed, and the slayer, after receiving God's pardon, having died as a martyr."*
* The man who had fought and killed a Muslim later became a Muslim himself and was killed in the course of jihad.
Sahl b. Hunaif reported God’s Messenger as saying, “If anyone asks God for martyrdom with a genuine purpose God will bring him to the dwellings of the martyrs, even if he dies on his bed.”
Abu Qatada told that God's Messenger got up among them and mentioned to them that jihad in God’s path and faith in God are the most excellent works. A man rose and asked, "Tell me, Messenger of God, if I am killed in God’s path will my sins be covered up?" He replied, "Yes, if you are killed in God's path while showing endurance, seeking your reward from God, advancing and not retreating." Then God’s Messenger said, "What did you say?”* He replied, "Tell me, if I am killed in God’s path will my sins be covered up?" God's Messenger said, "Yes, while you are showing endurance, seeking your reward from God, advancing and not retreating; but this does not include a debt, for Gabriel told me that."
*Mirqat iv, 176 quotes Tibi to explain the request to repeat his question when a reply had already been given. The purpose is said to be to make the exception at the end of the second reply.