Musnad Ahmad 937:232

Sulayman ibn Dawud Abu Dawud narrated to us, Abd al-Rahman ibn Thabit ibn Thawban narrated to us, my father narrated to me, from Makhul, from Ibn Nu'aym, that he narrated to him, that Abu Dharr narrated to them, that the Messenger of Allah (peace and blessings of Allah be upon him) says: "Indeed, Allah accepts the repentance of His servant, or forgives His servant, as long as the veil does not fall." It was said: "And what is the falling of the veil?" He said: "The soul departs while it is a polytheist."