“I have not seen any of Satan’s [ploys] a greater trap, nor uglier, nor more foolish, than two statements that he has cast upon the tongues of his proselytizers:

The first of the two: A person’s excusing his wrongdoing on the basis that such-and-such person has done wrong before him.

The second: A person’s dismissal of [the fact] that he is doing wrong today, on the basis that he [already] did wrong yesterday, or that [he may as well] do wrong in one thing because he has [already] done wrong is other things.”

— Ibn Hazm of Cordoba (d. 1064 CE / 456 H)

قال ابن حزم: لم أر لإبليس أصيد وَلَا أقبح وَلَا أَحمَق من كَلِمَتَيْنِ ألقاهما على أَلْسِنَة دعاته إِحْدَاهمَا اعتذار من أَسَاءَ بِأَن فلَانا أَسَاءَ قبله وَالثَّانيَِة استسهال الْإِنْسَان أَن يسيء
الْيَوْم لِأَنَّهُ قد أَسَاءَ أمس أَو أَن يسيء فِي وَجه مَا لِأَنَّهُ قد أَسَاءَ فِي غَيره

(من كتاب السيروالأخلاق)