[Machine] About the Prophet ﷺ , he said, "Do not count a prayer for a man who does not maintain his back or his spine during the bowing and prostration." This is the wording of the narration of Shu'bah. And in the narration of 'Ubaidullah, "without a doubt, his back," is mentioned. And it is also narrated by 'Umara ibn 'Umair, from Abu Ma'mar, from Abu Mas'ud who said, "He (the Prophet) said-"
عَنِ النَّبِيِّ ﷺ قَالَ لَا تُجْزِي صَلَاةٌ لِرَجُلٍ لَا يُقِيمُ صُلْبَهُ أَوْ قَالَ ظَهْرَهُ فِي الرُّكُوعِ وَالسُّجُودِ لَفْظُ حَدِيثِ شُعْبَةَ وَفِي حَدِيثِ عُبَيْدِ اللهِ صُلْبَهُ بِلَا شَكٍّ وَقَالَ عَنْ عُمَارَةَ بْنِ عُمَيْرٍ عَنْ أَبِي مَعْمَرٍ عَنْ أَبِي مَسْعُودٍ قَالَ قَالَ