(77) CHAPTER. Do not say that so-and-so is a martyr.
Narrated Abu Hurairah that the Prophet (صلى الله عليه وسلم) said, “Allah knows him who fights in His Cause, and Allah knows him who gets wounded in His Cause.”
2898. Narrated Sahl bin Sa’d As-Sa’idi (رضي الله عنه): Allah’s Messenger (صلى الله عليه وسلم) and Al-Mushrikin met each other in a battle and started fighting. When Allah’s Messenger (صلى الله عليه وسلم) returned to his camp and when Al-Mushrikin returned to their camp, somebody talked about a man amongst the companions of Allah’s Messenger (صلى الله عليه وسلم) who would follow and kill with his sword any Mushrik going alone. He (or they) said, “Nobody did his job (i.e. fighting) so properly today as that man.” Allah’s Messenger (صلى الله عليه وسلم) said, “Indeed, he is one of the people of the (Hell)Fire.” A man amongst the people said, “I shall accompany him (to watch what he does)”. Thus he accompanied him, and wherever he stood, he would stand with him, and wherever he ran, he would run with him. Then the (brave) man got wounded seriously and he hurried to die quickly. So he planted the blade of his sword in the ground directing its sharp end towards his chest between his two breasts. Then he leaned on the sword and killed himself. Another man came to Allah’s Messenger (صلى الله عليه وسلم) and said, “I testify that you are Allah’s Messenger (صلى الله عليه وسلم).” The Prophet (صلى الله عليه وسلم) asked, “What has happened?” He replied, “(It is about) the man whom you had described as one of the poeple of the (Hell)Fire. The people were greatly surprised at what you said, and I said, ‘I will find out his reality for you.’ So, I came out seeking him. He got severely wounded, and hastened to die by planting the blade of his sword in the ground directing its sharp end towards his chest between his two breasts. Then he leaned on his sword and killed himself.” Then Allah’s Messenger (صلى الله عليه وسلم) said, “A man may seem to the people as if he were doing the deeds of the people of Paradise, while in fact he is from the people of the (Hell)Fire, another may seem to the people as if he were doing the deeds of the people of Hell(Fire), while in fact he is from the people of Paradise.
Sahih Bukhari, Volume 4, The Book of Jihad, Chapter 77 (Do not say that so-and-so is a martyr, Maktaba Dar-us-Salam, 1997, pp.100-101.