Musnad Ahmad 788:196

'Affan and 'Abd al-Samad narrated to us, they said: Ja'far narrated to us—'Affan said in his narration: I heard Abu 'Imran al-Jawni saying: Abu Bakr ibn 'Abd Allah ibn Qays narrated to us, he said: I heard my father, while he was in the presence of the enemy, saying: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, the gates of Paradise are under the shadows of the swords." He said: Then a man from the people, disheveled in appearance, stood up and said: "O Abu Musa, did you hear the Prophet (peace and blessings of Allah be upon him) say this?" He said: "Yes." He said: So he returned to his companions and said: "I bid you peace," then he broke the scabbard of his sword, then walked with his sword toward the enemy, and struck with it until he was killed.