(17) باب الْخَصْرِ فِي الصَّلاَةِ
Narrated Abu Huraira:
It was forbidden to pray with the hands over one's hips.
Reference: Sahih al-Bukhari 1220
In-book reference: Book 21, Hadith 24
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 22, Hadith 311