[Machine] When Prophet Muhammad ﷺ would go to sleep at night, he would place his ritual purification (taharah) and his toothbrush (siwak) and comb (miswak) next to him. When Allah (SWT) would wake him up at night, he would use the toothbrush and perform ablution (wudu) and comb his hair. 'Uthman said, "This is something unknown." The sheikh replied that this narration from unknown sources is weak. Abu Sulayman al-Khattabi said Asma'iyy reported that the word "aaj" refers to the faded ivory, which is also known as the bony back of the sea turtle. As for the ivory that is known to the general public, it refers to the tusks of the elephant and it is a dead substance that is not permissible to be used.  

كَانَ النَّبِيُّ ﷺ إِذَا أَخَذَ مَضْجَعَهُ مِنَ اللَّيْلِ وَضَعَ طَهُورَهُ وَسِوَاكَهُ وَمِشْطَهُ فَإِذَا هَبَّهُ اللهُ تَعَالَى مِنَ اللَّيْلِ اسْتَاكَ وَتَوَضَّأَ وَامْتَشَطَ قَالَ وَرَأَيْتُ رَسُولَ اللهِ ﷺ يَتَمَشَّطُ بِمُشْطٍ مِنْ عَاجٍ قَالَ عُثْمَانُ هَذَا مُنْكَرٌ قَالَ الشَّيْخُ رِوَايَةُ بَقِيَّةَ عَنْ شِيُوخِهِ الْمَجْهُولِينَ ضَعِيفَةٌ وَقَدْ قَالَ أَبُو سُلَيْمَانَ الْخَطَّابِيُّ قَالَ الْأَصْمَعِيُّ الْعَاجُ الذَّبْلُ وَيُقَالُ هُوَ عَظْمُ ظَهْرِ السُّلَحْفَاةِ الْبَحْرِيَّةِ وَأَمَّا الْعَاجُ الَّذِي تَعْرِفُهُ الْعَامَّةُ فَهُوَ عَظْمُ أَنْيَابِ الْفِيَلَةِ وَهُوَ مَيْتَةٌ لَا يَجُوزُ اسْتِعْمَالُهُ