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.'" (PT)
English reference (PT): Vol. 1, Book 5, Hadith 873 (PT)
Arabic reference (PT): Book 5, Hadith 922 (PT)