عَنْ عَلَيِّ بْنِ شَيْبَانَ رَضِيَ اللَّهُ عَنْهُ أَنَّهُ خَرَجَ وَافِدًا إِلَى رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ: فَصَلَّيْنَا خَلْفَ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ فَلَمَحَ بِمُؤْخَرِ عَيْنَيْهِ إِلَى رَجُلٍ لَا يُقِيمُ صُلْبَهُ فِي الرُّكُوعِ وَالسُّجُودِ فَلَمَّا انْصَرَفَ قَالَ: ((يَا مَعْشَرَ الْمُسْلِمِينَ! إِنَّهُ لَا صَلَاةَ لِمَنْ لَا يُقِيمُ صُلْبَهُ فِي الرُّكُوعِ وَالسُّجُودِ))
It is narrated from Sayyiduna Ali bin Shiban (may Allah be pleased with him), he says: I came to the Messenger of Allah (peace and blessings be upon him) as part of a delegation. We performed prayer behind the Noble Prophet. The Prophet glanced from the corner of his eye at a man who was not straightening his back in bowing (ruku) and prostration (sujud). When the Prophet (peace and blessings be upon him) finished the prayer, he said: O assembly of Muslims! Indeed, that man has no prayer, who does not straighten his back in bowing and prostration.