Sunnan Abu Dawud Collection: ::Book Number 38:: Hadith # 4345
Narrated Abdullah ibn Abbas: Abdullah ibn AbuSarh used to write (the revelation) for the Apostle of Allah (peace_be_upon_him). Satan made him slip, and he joined the infidels. The Apostle of Allah (peace_be_upon_him) commanded to kill him on the day of Conquest (of Mecca). Uthman ibn Affan sought protection for him. The Apostle of Allah (peace_be_upon_him) gave him protection.