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 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.
Anas told that ar-Rubaiyi‘ daughter of al-Bara’, who was the mother of Haritha b. Suraqa, came to the Prophet and said, “Prophet of God, will you not tell me about Haritha? (He had been killed at the battle of Badr, being struck by a random arrow.) If he is in paradise I shall show endurance, but if he has met another fate I shall exert myself in weeping for him.” He replied, “Mother of Haritha, in paradise there are gardens, and your son has attained to al-Firdaus, the highest.”