Mustadrak al-Hakim — Hadith 4919

Abd al-Rahman bin Ka'b bin Malik narrates concerning his father; he said: I used to lead my father after he had lost his sight. Whenever he heard the adhan for Jumu'ah, he would say: "May Allah's mercy be upon As'ad bin Zurarah." After some time I thought I would ask my father why, on hearing the adhan, he prayed for mercy for As'ad bin Zurarah. I said: "O my father, whenever you hear the adhan for Jumu'ah, this prayer of yours for Abu Umamah (As'ad) strikes me; what is the reason for it?" He said: "O my dear son, he was the first to establish the Jumu'ah prayer for us in Madinah, at a level spot in the Harrah of Banu Bayadah called Naqi' al-Khadimat." I asked: "How many of you were there that day?" He said: "Forty men."