Sahih Muslim Book 37, Hadith Number 6672.

Chapter : Pertaining to the repentance of Ka’b b. Malik and his companions.

It is reported on the authority of Abdullah b. K’ab and he was the guide of Ka’b as he lost his eyesight and he was the greatest scholar amongst his people and he retained in his mind many ahadith of the Companions of Allah’s Messenger (may peace be upon him). He said: I heard my father Ka’b b. Malik, and he has one of those three whose repentance was accepted (by Allah). He transmitted that He never lagged behind Allah’s Messenger (may peace be upon him) from any expedition that he undertook except two expeditions; the rest of the hadith is the same, and in the tradition narrated through another chain of transmitters the words are: “That Allah’s Messenger (may peace be upon him) set out on an expedition with a large number of persons more than ten thousand and this could not be recorded in the census register.”