“We set out until we came to the Messenger of Allah ﷺ, and we gave him our oath of allegiance and performed prayer behind him. He glanced out of the corner of his eye at a man who was not settling his spine when he bowed and prostrated. When the Prophet ﷺ finished the prayer, he said: ‘O Muslims, there is no prayer for the one who does not settle his spine when bowing and prostrating.’”
خَرَجْنَا حَتَّى قَدِمْنَا عَلَى رَسُولِ اللَّهِ ﷺ فَبَايَعْنَاهُ وَصَلَّيْنَا خَلْفَهُ فَلَمَحَ بِمُؤْخِرِ عَيْنِهِ رَجُلاً لاَ يُقِيمُ صَلاَتَهُ يَعْنِي صُلْبَهُ فِي الرُّكُوعِ وَالسُّجُودِ فَلَمَّا قَضَى النَّبِيُّ ﷺ الصَّلاَةَ قَالَ يَا مَعْشَرَ الْمُسْلِمِينَ لاَ صَلاَةَ لِمَنْ لاَ يُقِيمُ صُلْبَهُ فِي الرُّكُوعِ وَالسُّجُودِ