Sahih al-Bukhari 4207

Narrated Sahl:During one of his Ghazawat, the Prophet (ﷺ) encountered the pagans, and the two armies fought, and then each of them returned to their army camps. Amongst the (army of the) Muslims there was a man who would follow every pagan separated from the army and strike him with his sword. It was said, "O Allah's Messenger (ﷺ)! None has fought so satisfactorily as so-and-so (namely, that brave Muslim). "The Prophet said, "He is from the dwellers of the Hell-Fire." The people said, "Who amongst us will be of the dwellers of Paradise if this (man) is from the dwellers of the Hell-Fire?" Then a man from amongst the people said, "I will follow him and accompany him in his fast and slow movements." The (brave) man got wounded, and wanting to die at once, he put the handle of his sword on the ground and its tip in between his breasts, and then threw himself over it, committing suicide. Then the man (who had watched the deceased) returned to the Prophet (ﷺ) and said, "I testify that you are Apostle of Allah." The Prophet (ﷺ) said, "What is this?" The man told him the whole story. The Prophet (ﷺ) said, "A man may do what may seem to the people as the deeds of the dwellers of Paradise, but he is of the dwellers of the Hell-Fire and a man may do what may seem to the people as the deeds of the dwellers of the Hell-Fire, but he is from the dwellers of Paradise."