Sahih Muslim 209 a
It is reported on the authority of 'Abbas b. Abd al-Muttalib that he said:
Messenger of Allah, have you benefited Abu Talib in any way for he defended you and was fervent in your defence? The Messenger of Allah (may peace he upon him) said: Yes; he would be in the most shallow part of the Fire and were not for me, he would have been in the bottom-most depth of Hell.
وَحَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ عُمَرَ الْقَوَارِيرِيُّ، وَمُحَمَّدُ بْنُ أَبِي بَكْرِ الْمُقَدَّمِيُّ، وَمُحَمَّدُ بْنُ عَبْدِ الْمَلِكِ الأُمَوِيُّ، قَالُوا حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ عَبْدِ الْمَلِكِ بْنِ عُمَيْرٍ، عَنْ عَبْدِ اللَّهِ بْنِ الْحَارِثِ بْنِ نَوْفَلٍ، عَنِ الْعَبَّاسِ بْنِ عَبْدِ الْمُطَّلِبِ، أَنَّهُ قَالَ يَا رَسُولَ اللَّهِ هَلْ نَفَعْتَ أَبَا طَالِبٍ بِشَىْءٍ فَإِنَّهُ كَانَ يَحُوطُكَ وَيَغْضَبُ لَكَ قَالَ ‏
"‏ نَعَمْ هُوَ فِي ضَحْضَاحٍ مِنْ نَارٍ وَلَوْلاَ أَنَا لَكَانَ فِي الدَّرْكِ الأَسْفَلِ مِنَ النَّارِ ‏"‏ ‏.‏