حَدَّثَنَا إِبْرَاهِيمُ بْنُ الْمُنْذِرِ الْحِزَامِيُّ، حَدَّثَنَا بَكْرُ بْنُ سُلَيْمٍ، حَدَّثَنِي حُمَيْدُ بْنُ زِيَادٍ الْخَرَّاطُ، عَنْ كُرَيْبٍ، مَوْلَى عَبْدِ اللَّهِ بْنِ عَبَّاسٍ قَالَ هَلَكَ ابْنٌ لِعَبْدِ اللَّهِ بْنِ عَبَّاسٍ فَقَالَ لِي يَا كُرَيْبُ قُمْ فَانْظُرْ هَلِ اجْتَمَعَ لاِبْنِي أَحَدٌ فَقُلْتُ نَعَمْ ‏.‏ فَقَالَ وَيْحَكَ كَمْ تَرَاهُمْ أَرْبَعِينَ قُلْتُ لاَ بَلْ هُمْ أَكْثَرُ ‏.‏ قَالَ فَاخْرُجُوا بِابْنِي فَأَشْهَدُ لَسَمِعْتُ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ يَقُولُ ‏"‏ مَا مِنْ أَرْبَعِينَ مِنْ مُؤْمِنٍ يَشْفَعُونَ لِمُؤْمِنٍ إِلاَّ شَفَّعَهُمُ اللَّهُ ‏"‏ ‏.‏

It wasnarrated that Kuraib the freed slave of ‘Abdullah bin ‘Abbassaid: “A son of ‘Abdullah bin ‘Abbas died, and he said to me:‘OKuraib! Get up and see if anyone has assembled (to pray) for myson.’I said: ‘Yes.’ He said: ‘Woe to you, how many do yousee? Forty?’ Isaid: ‘No, rather there are more.’ He said:‘Take my son out, for Ibear witness that I hear the Messenger ofAllah (PBUH) say: “No (groupof) forty believers intercede for abeliever, but Allah will accepttheir intercession.” Translation Not Available

Book Ref: Sunan Ibn Majah Book 6 Hadith 1489
Web Ref:  Sunan Ibn Majah Vol 1 Book 6 Hadith 1489