It wasnarrated that Mus'ab bin Sa'd said:
"I bowed (in prayer)besidemy father, and I put my hands between my knees. He struck myhand andsaid: 'We used to do that, then we were commanded to put themonthe knees.'" (RU)
English reference (RU): Vol. 1, Book 5, Hadith 873 (RU)
Arabic reference (RU): Book 5, Hadith 922 (RU)