What is the correct posture during prostration (*Sujud*)?

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When descending into prostration, the Messenger of Allah, peace be upon him, would separate his hands from his sides. Upon returning from prostration, he would straighten his back, supporting himself by sitting on his left foot, ensuring that all bones returned to their place. When prostrating, he would open the tips of his toes. He did not sit *Iftirash* (spreading the foot) or grasp with his hands during the prostration itself.