If one is unable to prostrate, should he place his hands on the ground?

Question : Yes, if we assume that he is unable to prostrate at all, meaning his back is completely unable to do so,

Answer : in that case, we do not say that you are required to place your hands on the ground. For example, if we assume that he can only do this, like this, and cannot do more than that. In this case, we do not say that you are required to place your hands on the ground, because there is no benefit in doing so; rather, this may resemble squatting. However, if he is able to approach the ground so that he is in the posture of one who is prostrating, then it is obligatory for him to do what? He must prostrate. He must prostrate and bring his forehead as close to the ground as he is able.