Putting the hand on the waist is disliked; because it involves abandoning the prescribed position. Abu Huraira (may Allah be pleased with him) reported that the Prophet (peace be upon him) forbade a man from praying while holding his waist, as mentioned in Sahih Muslim 1: 387. Abu Huraira (may Allah be pleased with him) also said that the Prophet (peace be upon him) stated: "Holding the waist in prayer is a comfort for the people of Hell," as found in Sahih Ibn Hibban 6: 63 and Sahih Ibn Khuzaymah 2: 57. See: Al-Bada'i 1: 215, and Al-Tabeen 1: 163.