Musnad Abu Ya'la al-Mawsili 1:88

Muhammad ibn al-Faraj narrated to us, Muhammad ibn al-Zibriqan narrated to us, Musa ibn Ubaydah narrated to us, Hud ibn Ata informed me, from Anas ibn Malik, who said: There was a man during the time of the Messenger of Allah (may Allah bless him and grant him peace) whose worship and diligence impressed us. We mentioned him to the Messenger of Allah (may Allah bless him and grant him peace) by his name, but he did not recognize him. We described him by his attributes, but he did not recognize him. While we were mentioning him, the man appeared. We said, "There he is." He said, "You are telling me about a man upon whose face is a mark (suf'ah) from Satan." He approached until he stood over them and did not offer the greeting of peace. The Messenger of Allah (may Allah bless him and grant him peace) said to him, "I adjure you by Allah, did you say when you stood over the gathering, 'There is no one among the people better than me or more virtuous than me'?" He said, "O Allah, yes." Then he entered to pray. The Messenger of Allah (may Allah bless him and grant him peace) said, "Who will kill the man?" Abu Bakr said, "I will." He entered upon him and found him standing in prayer. He said, "Subhan Allah! Shall I kill a man who is praying, when the Messenger of Allah (may Allah bless him and grant him peace) has forbidden the killing of those who pray?" He went out. The Messenger of Allah (may Allah bless him and grant him peace) said, "What did you do?" He said, "I disliked killing him while he was praying, and I have been forbidden from killing those who pray." Umar said, "I will." He entered and found him with his face placed [on the ground in prostration]. Umar said, "Abu Bakr is better than me." He went out. The Messenger of Allah (may Allah bless him and grant him peace) said, "What is the matter?" He said, "I found him with his face placed [on the ground], so I disliked killing him." He said, "Who will kill the man?" Ali said, "I will." He said, "You, if you catch him." Ali entered and found that he had left. He returned to the Messenger of Allah (may Allah bless him and grant him peace). He said, "What is the matter?" He said, "I found that he had left." He said, "If he had been killed, no two men in my nation would have differed, from the first of them to the last of them." Musa said: I heard Muhammad ibn Ka'b say: "He is the one whom Ali killed, Dhu al-Thudayyah."