Is unintentional movement during prayer—such as trembling while prostrating or bowing—incompatible with ṭumaʾnīnah (tranquility), which is the stillness of limbs for the duration of one tasbīḥah? And must prayers performed in this manner be repeated?

"Tranquility is obligatory in the physical pillars of prayer. It means the stillness and stability of the limbs. The sufficient degree of tranquility is the stability of the limbs for a period of time during which there is a separation between the pillar the worshipper is moving to and the pillar he was in. Shaking during bowing or prostration does not negate tranquility or invalidate the prayer if the worshipper achieves the sufficient degree of tranquility."