Musannaf Ibn Abi Shayba 28:727

Marwan ibn Mu'awiyah narrated to us, from Humayd, from Habib Abu Yahya, that Khalid ibn Zayd—and his eye had been afflicted with a disease—said: We besieged their city and encountered hardship, and the commander of the Muslims was Abu Musa. The chieftain took his pledge and the pledge of those who were with him. Abu Musa said, "Separate them." He began to separate them, and Abu Musa began saying to his companions, "I hope that Allah will deceive him regarding himself." He separated them, and the enemy of Allah remained. Abu Musa ordered him [to be executed], so he called out and offered much wealth, but he refused, and he struck his neck.