وَعَلِمْتُ أَنَّ المُسْتَحِيلَ ثَلاثَةٌ
الغُولُ وَالعَنْقَاءُ وَالخِلُّ الوَفِي
And I learned that the impossible are three:
The ghoul, the phoenix, and the loyal friend
المصدر · Source: Diwan al-Mutanabbi. Sharh al-Ukbari