It was narrated that Kuraib the freed slave of 'Abdullah bin 'Abbas said: "A son of 'Abdullah bin 'Abbas died, and he said to me: '0 Kuraib! Cet up and see if anyone has assembled (to pray) for my son.' I said: 'Yes.' He said: 'Woe to you, how many do you see? Forty?' I said: 'No, rather there are more.' He said: 'Take my son out, for J bear witness that I heard the Messenger of Allah P.B.U.H say: "No (group of) forty believers intercede for a believer, but Allah will accept their intercession." (Sahih)