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