[Machine] The Prophet ﷺ was commanded to prostrate on seven bones, without folding his garment or letting his hair touch the ground.  

أُمِرَ رَسُولُ اللهِ ﷺ أَنْ يَسْجُدَ عَلَى سَبْعَةِ أَعْظُمٍ وَلَا يَكُفَّ ثَوْبًا وَلَا شَعْرًا  

[Machine] I heard the Messenger of Allah ﷺ saying, "Indeed, the example of this is like that of one who prays while his hands are tied." This hadith was narrated by Muslim in his Sahih from 'Amr bin Sawwad from Ibn Wahb.  

سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ إِنَّمَا مَثَلُ هَذَا مَثَلُ الَّذِي يُصَلِّي وَهُوَ مَكْتُوفٌ وَرَوَاهُ مُسْلِمٌ فِي الصَّحِيحِ عَنْ عَمْرِو بْنِ سَوَّادٍ عَنِ ابْنِ وَهْبٍ  

[Machine] Abu Rafi`, the servant of the Prophet ﷺ , passed by Hasan ibn Ali. Hasan was standing in prayer, with his fingernails digging into his cheeks. Abu Rafi` loosened them, and Hasan turned to him angrily. Abu Rafi` said, "Continue with your prayer and don't get angry, for I heard the Messenger of Allah ﷺ say that this is the seat of Satan. It means digging one's fingernails into one's cheeks." This narration is reported by Hajjaj ibn Muhammad and mentioned by Abdul Razzaq from Sa`id. And it is narrated that Umar, Ali, Hudhaifah, and Abdullah ibn Mas`ud disliked doing this.  

أَبَا رَافِعٍ مَوْلَى النَّبِيِّ ﷺ مَرَّ بِحَسَنِ بْنِ عَلِيٍّ وَحَسَنٌ يُصَلِّي قَائِمًا قَدْ غَرَزَ ضَفْرَتَيْهِ فِي قَفَاهُ فَحَلَّهُمَا أَبُو رَافِعٍ فَالْتَفَتَ حَسَنٌ إِلَيْهِ مُغْضَبًا فَقَالَ أَبُو رَافِعٍ أَقْبِلْ عَلَى صَلَاتِكَ وَلَا تَغْضَبْ فَإِنِّي سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ ذَلِكَ كِفْلُ الشَّيْطَانِ يَقُولُ مَقْعَدُ الشَّيْطَانِ يَعْنِي مَغْرِزَ ضَفْرَتَيْهِ لَفْظُ حَدِيثِ حَجَّاجِ بْنِ مُحَمَّدٍ وَفِي حَدِيثِ عَبْدِ الرَّزَّاقِ عَنْ سَعِيدٍ وَقَالَ هِيَ كِفْلُ الشَّيْطَانِ يَعْنِي مَقْعَدَ الشَّيْطَانِ وَرُوِّينَا فِي كَرَاهِيَةِ ذَلِكَ عَنْ عُمَرَ وَعَلِيٍّ وَحُذَيْفَةَ وَعَبْدِ اللهِ بْنِ مَسْعُودٍ ؓ