Is it disliked to pray with hands on the waist (clasping the hands behind the back)?
Chapter on what invalidates the prayer if omitted intentionally or forgetfully
Al-Mughni
Book of Prayer
Primary text
It is disliked to pray with the hand on the waist (clasping). Abu Hurairah narrated that the Prophet, peace be upon him, forbade a man from praying while clasping his hands. Ziyad ibn Subayh Al-Hanafi reported that Ibn Umar told him placing the hand on the waist is rigidity ('Sulb') in prayer and that the Messenger of Allah, peace be upon him, forbade it (narrated by Abu Dawud).