Why do you not consider it obligatory to place the right hand over the left in prayer, even though the Messenger commands us to pray as he prayed — may God’s peace and blessings be upon him?

None of the jurists, except for the Zahirites, have stated the obligation of placing the right hand over the left in prayer. Rather, the majority are of the opinion that it is sunnah (recommended). The correct view attributed to Malik is that he considers grasping (the hands) to be sunnah, like other imams. The reason they did not deem it obligatory is that placing the right hand over the left is one of the postures of prayer, not an independent act of worship.