Mukhtasar Muslim (Abridged) 293 — Placing both hands on knees

Mus'ab bin Sa'd narrates that I prayed next to my father and placed my hands between my knees, so my father said to me, "Place both your palms on your knees." Mus'ab said that then I did the same again, so he struck my hand and said, "We have been forbidden from doing this and have been commanded to place both palms on the knees in (ruku')."