When his men were overpowered by Muawiya''s men
Nahj al-Balāgha|Volume 1|Book 1|Chapter 25
مَا هِيَ إِلاَّ الكُوفَةُ، أقْبِضُهَا وَأَبْسُطُهَا، إنْ لَمْ تَكُوني إِلاَّ أَنْتِ، تَهُبُّ أَعَاصِيرُك، فَقَبَّحَكِ اللهُ!
Nothing (is left to me) but Kūfah which I can hold and extend (which is in my hand to play with). (O Kūfah) if this is your condition that whirlwinds continue blowing through you then Allah may destroy you.