The Umayyads made sport of him, so he went back to ʿAlī.

Muʿāwiyah then wrote to Marwān: “What have you done by sending Qays over to him?”

The narrator adds: Ibn Hudayj and his followers also wrote to Muʿāwiyah, saying: “Send us a leader.”

So he dispatched ʿAmr ibn al-ʿĀṣ to them. Muḥammad ibn Abī Bakr sought refuge with an elderly woman, but her son pointed him out; they killed him, placed his body inside the belly of a donkey, and burned it. Muḥammad ibn Abī Hudhayfah fled and was likewise killed. (1)

Al-Zuhrī relates:
Qays arrived in Medina. Al-Aswad ibn Abī al-Bakhtarī and Marwān conspired to attack him by night, and word of this reached Qays. He said, “By Allah, it is shameful (2) for me to part from ʿAlī—even if he has removed me. By Allah, I shall certainly return to him.”

He did return, told ʿAlī what he had been doing in Egypt, and ʿAlī realised that Qays had been handling a grave matter with subtle strategy. ʿAlī therefore deferred (3) to Qays in every decision and placed him at the head of his army.

Muʿāwiyah then sent a message of reproach(4) to Marwān and al-Aswad, saying, “Have you reinforced(5) ʿAlī with Qays? By Allah, had you reinforced him with one hundred thousand fighters, it would not have angered me more than your sending Qays to him!”(6)

A similar report is transmitted by Maʿmar from al-Zuhrī.

Hishām ibn ʿUrwah, on the authority of his father, said:
Qays was at the forefront of ʿAlī’s forces with five thousand men who had shaved their heads. After ʿAlī’s death, when al-Ḥasan (7) pledged allegiance to Muʿāwiyah, Qays refused to enter the pledge and said to his men, “If you wish, I will fight on with you until the first of us is killed; but if you prefer, I will secure safe-conduct for you.”
They replied, “Secure it for us.”