(81) باب مَا جَاءَ فِيمَنْ لاَ يُقِيمُ صُلْبَهُ فِي الرُّكُوعِ وَالسُّجُودِ
Abu Mas'ud Al-Ansari [Al-Badri] narrated that :
Allah's Messenger said: "The Salat is not acceptable if a man is not at rest - meaning his back - while bowing and prostrating." (DE)
Reference (DE): Jami` at-Tirmidhi 265 (DE)
In-book reference (DE): Book 2, Hadith 117 (DE)
English translation (DE): Vol. 1, Book 2, Hadith 265 (DE)