رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 1752
The Book of the Prohibited actions
Prohibition of Placing the hands on the sides during As-Salat (The Prayer)
عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّه عَنْهُ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ: نَهَى عَنْ الخصر في الصلاة. ((مُتَّفَقٌ عَلَيْهِ)).
Abu Hurairah (May Allah be pleased with him) said: We are prohibited from placing the hand on the side during As-Salat (the prayer). [Al-Bukhari and Muslim].
Riyad as-Salihin, 1752