Musannaf Ibn Abi Shayba 33:803

Muhammad ibn Fudayl narrated to us, from ‘Asim, from Thabit al-Bunani, who said: A man from the companions of Muhammad narrated to me, by this pillar, he said: Whoever says, "Subhan Allah wa bihamdihi, wa astaghfirullaha wa atubu ilayh" (Glory be to Allah and by His praise, and I seek forgiveness from Allah and repent to Him), it is written on a parchment, then a seal of musk is placed upon it. It is not broken until it is brought forth with it on the Day of Resurrection.