Narrated Khabbab bin Al-Arat:

We complained to Allah's Apostle (of the persecution inflicted on us by the infidels) while he was sitting in the shade of the Ka'ba, leaning over his Burd (i.e. covering sheet). We said to him, "Would you seek help for us? Would you pray to Allah for us?" He said, "Among the nations before you a (believing) man would be put in a ditch that was dug for him, and a saw would be put over his head and he would be cut into two pieces;
yet that (torture) would not make him give up his religion. His body would be combed with iron combs that would remove his flesh from the bones and nerves, yet that would not make him abandon his religion. By Allah, this religion (i.e. Islam) will prevail till a traveler from Sana (in Yemen) to Hadrarmaut will fear none but Allah, or a wolf as regards his sheep, but you (people) are hasty.

حَدَّثَنِي مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا يَحْيَى، عَنْ إِسْمَاعِيلَ، حَدَّثَنَا قَيْسٌ، عَنْ خَبَّابِ بْنِ الأَرَتِّ، قَالَ شَكَوْنَا إِلَى رَسُولِ اللَّهِ ﷺ وَهْوَ مُتَوَسِّدٌ بُرْدَةً لَهُ فِي ظِلِّ الْكَعْبَةِ، قُلْنَا لَهُ أَلاَ تَسْتَنْصِرُ لَنَا أَلاَ تَدْعُو اللَّهَ لَنَا قَالَ
" كَانَ الرَّجُلُ فِيمَنْ قَبْلَكُمْ يُحْفَرُ لَهُ فِي الأَرْضِ فَيُجْعَلُ فِيهِ، فَيُجَاءُ بِالْمِنْشَارِ، فَيُوضَعُ عَلَى رَأْسِهِ فَيُشَقُّ بِاثْنَتَيْنِ، وَمَا يَصُدُّهُ ذَلِكَ عَنْ دِينِهِ، وَيُمْشَطُ بِأَمْشَاطِ الْحَدِيدِ، مَا دُونَ لَحْمِهِ مِنْ عَظْمٍ أَوْ عَصَبٍ، وَمَا يَصُدُّهُ ذَلِكَ عَنْ دِينِهِ، وَاللَّهِ لَيُتِمَّنَّ هَذَا الأَمْرَ حَتَّى يَسِيرَ الرَّاكِبُ مِنْ صَنْعَاءَ إِلَى حَضْرَمَوْتَ، لاَ يَخَافُ إِلاَّ اللَّهَ أَوِ الذِّئْبَ عَلَى غَنَمِهِ، وَلَكِنَّكُمْ تَسْتَعْجِلُونَ ".