Sunan an-Nasa'i
Sunan an-Nasa'i 1111
أَخْبَرَنَا عَلِيُّ بْنُ خَشْرَمٍ الْمَرْوَزِيُّ، قَالَ أَنْبَأَنَا عِيسَى، - وَهُوَ ابْنُ يُونُسَ - عَنِ الأَعْمَشِ، عَنْ عُمَارَةَ، عَنْ أَبِي مَعْمَرٍ، عَنْ أَبِي مَسْعُودٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ تُجْزِئُ صَلاَةٌ لاَ يُقِيمُ الرَّجُلُ فِيهَا صُلْبَهُ فِي الرُّكُوعِ وَالسُّجُودِ " .
‘Ali ibn Khashram al-Marwazi reported to us; he said: ‘Isa—namely, Ibn Yunus—informed us, from al-A‘mash, from ‘Umarah, from Abu Ma‘mar, from Abu Mas‘ud, who said: The Messenger of Allah (ﷺ) said: ‘A prayer is not sufficient if a man does not straighten his back during bowing and prostration.’
Translation notes
لاَ تُجْزِئُ صَلاَةٌ is rendered “a prayer is not sufficient”; يُقِيمُ صُلْبَهُ means to keep/straighten one’s back. The English witness renders the same sense as “no prayer is valid.”