Sa’ad from Muhammad ibn Khalid al-Tayalisi from Ibrahim ibn Abi Ziyad al-Karkhi who said: I said to Abu Abdillah عليه السلام, peace be upon him: “An old man is unable to stand, to go to the toilet, and he cannot perform bowing (rukuh) and prostration (sujud).” Imam عليه السلام said: “Then let him gesture with his head by indication (ima'a), and if there is someone who can raise the khumrah (a small prayer mat or place of prostration) to him, then let him prostrate on it. If that is not possible for him, then let him gesture with his head in the direction of the qiblah by indication.” I asked: “And what about fasting?” Imam عليه السلام said: “If he has reached that condition, then Allah سبحانه وتعالى has lifted the obligation from him. But if he is able, then giving in charity a mudd of food in place of each day is more beloved to me. And if he does not have the means for that, then there is nothing upon him.”