Sunan Ibn Majah, Chapter: Chapters Regarding Funerals

the freed slave of Abdullah bin Abbas: "A son of Abdullah bin 'Abbas died, and he said to me: 'O Kuraib! Get 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 I bear witness that I hear the Messenger of Allah (saw) say: "No (group of) forty believers intercede for a believer, but Allah will accept their intercession." Daif