Sunan Abi Dawud, Hadith 2643

Khabbab said “We came to the Apostle of Allaah while he was reclining on an outer garment in the shade of the Ka’bah. Complaining to him we said “Do you not ask Allaah for help for us? And do you not pray to Allaah for us? He sat aright turning red in his face and said “A man before you (i.e., in ancient times) was caught and a pit was dug for him in the earth and then a saw was brought placed on his head and it was broken into two pieces but that did not turn him away from his religion. They were combed in iron combs in flesh and sinews above the bones. Even that did not turn them away from their religion. I swear by Allaah, Allaah will accomplish this affair until a rider will travel between San’a and Hadramaut and he will not fear anyone except Allaah, Most High(nor will he fear the attack of) a wolf on his sheep, but you are making haste.

حَدَّثَنَا عَمْرُو بْنُ عَوْنٍ، أَخْبَرَنَا هُشَيْمٌ، وَخَالِدٌ، عَنْ إِسْمَاعِيلَ، عَنْ قَيْسِ بْنِ أَبِي حَازِمٍ، عَنْ خَبَّابٍ، قَالَ أَتَيْنَا رَسُولَ اللَّهِ صلى الله عليه وسلم وَهُوَ مُتَوَسِّدٌ بُرْدَةً فِي ظِلِّ الْكَعْبَةِ فَشَكَوْنَا إِلَيْهِ فَقُلْنَا أَلاَ تَسْتَنْصِرْ لَنَا أَلاَ تَدْعُو اللَّهَ لَنَا فَجَلَسَ مُحْمَرًّا وَجْهُهُ فَقَالَ ‏ "‏ قَدْ كَانَ مَنْ قَبْلَكُمْ يُؤْخَذُ الرَّجُلُ فَيُحْفَرُ لَهُ فِي الأَرْضِ ثُمَّ يُؤْتَى بِالْمِنْشَارِ فَيُجْعَلُ عَلَى رَأْسِهِ فَيُجْعَلُ فِرْقَتَيْنِ مَا يَصْرِفُهُ ذَلِكَ عَنْ دِينِهِ وَيُمْشَطُ بِأَمْشَاطِ الْحَدِيدِ مَا دُونَ عَظْمِهِ مِنْ لَحْمٍ وَعَصَبٍ مَا يَصْرِفُهُ ذَلِكَ عَنْ دِينِهِ وَاللَّهِ لَيُتِمَّنَّ اللَّهُ هَذَا الأَمْرَ حَتَّى يَسِيرَ الرَّاكِبُ مَا بَيْنَ صَنْعَاءَ وَحَضْرَمَوْتَ مَا يَخَافُ إِلاَّ اللَّهَ تَعَالَى وَالذِّئْبَ عَلَى غَنَمِهِ وَلَكِنَّكُمْ تَعْجَلُونَ ‏" ‏ ‏.‏

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also referenced under: Hadith 2649 (DarusSalam)