"Shall I not tell you about the prayer of the Messenger of Allah ﷺ? He stood and raised his hands the first time and then he did not do that again."  

أَلاَ أُخْبِرُكُمْ بِصَلاَةِ رَسُولِ اللَّهِ ﷺ قَالَ فَقَامَ فَرَفَعَ يَدَيْهِ أَوَّلَ مَرَّةٍ ثُمَّ لَمْ يُعِدْ  

"The Messenger of Allah ﷺ said: 'The prayer is not valid if a man does not bring his backbone to rest while bowing and prostrating.'"  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ تُجْزِئُ صَلاَةٌ لاَ يُقِيمُ الرَّجُلُ فِيهَا صُلْبَهُ فِي الرُّكُوعِ وَالسُّجُودِ  

"Be moderate in bowing and prostration, and do not rest your forearms along the ground like a dog."  

عَنْ رَسُولِ اللَّهِ ﷺ قَالَ اعْتَدِلُوا فِي الرُّكُوعِ وَالسُّجُودِ وَلاَ يَبْسُطْ أَحَدُكُمْ ذِرَاعَيْهِ كَالْكَلْبِ