Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) forbade a man to pray with his hands on his hips.
(b) In another narration the word "naha" (he forbade) is used.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3563