It is also said that, in the pre-Islamic period, his teknonym was Abū Bashīr.
Ibn Abī Ḥātim records that Kaʿb was one of the People of the Bench and that he lost his eyesight during the caliphate of Muʿāwiyah.⦗1⦘
ʿUrwah lists him among the seventy who attended the pact of al-ʿAqabah.
Ṣadaqah ibn Sābiq, transmitting from Ibn Isḥāq, relates that the Messenger of Allah ﷺ established a bond of brotherhood between Ṭalḥah ibn ʿUbayd Allah and Kaʿb ibn Mālik. Others say that he rather paired Kaʿb with al-Zubayr.
Hammād ibn Salamah reports—through Hishām ibn ʿUrwah, from his father—that the Messenger of Allah ﷺ did in fact make al-Zubayr and Kaʿb ibn Mālik brothers. Kaʿb was carried off wounded on the Day of Uḥud, and al-Zubayr came leading him. Had Kaʿb died that day, al-Zubayr would have inherited from him; whereupon Allah revealed: “But those bound by blood are nearer to one another in the Book of Allah” (Qurʾān 8:75).⦗2⦘⦗3⦘
Kaʿb himself relates: “When we broke ranks on the Day of Uḥud, I was the first to recognize the Messenger of Allah ﷺ and to proclaim to the believers that he was alive and unharmed, while I was in the mountain pass. The Messenger of Allah ﷺ then called for Kaʿb’s suit of armor, which was yellow. Kaʿb put it on and fought with great valor that day until he sustained seventeen wounds.”⦗4⦘