إِذَا سَاءَ فِعْلُ المَرْءِ سَاءَتْ ظُنُونُهُ
وَصَدَّقَ مَا يَعْتَادُهُ مِنْ تَوَهُّمِ
When a person's deed is evil, their suspicions become evil
And they believe what they habitually imagine
المصدر · Source: Diwan al-Mutanabbi. Sharh al-Wahidi