حَدَّثَنَا حَفْصُ بْنُ عُمَرَ النَّمَرِيُّ حَدَّثَنَا شُعْبَةُ عَنْ سُلَيْمَانَ عَنْ عُمَارَةَ بْنِ عُمَيْرٍ عَنْ أَبِي مَعْمَرٍ عَنْ أَبِي مَسْعُودٍ الْبَدْرِيِّ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّی اللَّهُ عَلَيْهِ وَسَلَّمَ لَا تُجْزِئُ صَلَاةُ الرَّجُلِ حَتَّی يُقِيمَ ظَهْرَهُ فِي الرُّکُوعِ وَالسُّجُودِ
سنن ابودوٗد · Hadith 855
Narrated Abu Masud al-Badri: The Prophet ﷺ said: A man's prayer does not avail him unless he keeps his back steady when bowing and prostrating.
Translated by Dr. Muhammad Muhsin Khan · Reviewed by Islamic University of Madinah · Published March 2020