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