When Allaah Wills Good For His Slave, By Ibn Al-Qayyim
Ibn Al-Qayyim said:
“When Allaah (swt) wills good for His save, He causes him to forget his acts of obedience and erases them from his mind and from his lips (so that he does not speak about them).
But if he commits a sin, He makes him think about his sin all the time and forget his good deeds, so that he focuses constantly on his sin, when he stands up or sits down, when he comes an goes. This is the essence of mercy concerning him.”
[Madaarij As-Saalikeen, 1/177]