Reference: al-Hifth – Ahammiyyatuhu, ‘Ajaa.ibuhu, Tareeqatuhu, Asbaabuhu – Page 67
‘Abdullaah ibn Mas’ood (radhi-yAllaahu ‘anhu) said:
Certainly, I consider a man who has forgotten knowledge which he used to possess to be the result of the sins he used to do.
