Musannaf Ibn Abi Shayba 28:262

'Abd al-Rahim ibn Sulayman narrated to us, from Ash'ath, from al-Sha'bi, who claimed that a man from Murad arrived. When Abu Musa had finished the prayer, the man stood up and said, "This is the station of the repentant, the seeker of refuge." Abu Musa said, "Woe to you, what is the matter with you?" He said, "I am so-and-so, son of so-and-so, the Muradi. I had waged war against Allah and His Messenger and strove in the land to cause corruption. This is the time I have come, and I have repented before you were able to seize me." Abu Musa stood in the place where he had stood, then said, "This is so-and-so, son of so-and-so, the Muradi. He had waged war against Allah and His Messenger and strove in the land to cause corruption, and he has repented before we were able to seize him. If he is truthful, then he is on the path of those who are truthful, and if he is a liar, Allah will take him for his sin." He said: So he went out among the people and departed, and he grew a beard, then he returned and was killed.