A person who cannot perform Hajj or ‘Umrah as a result of old age, permanent illness, or some weakness in his body due to which he cannot make the journey, should have somebody perform Hajj and ‘Umrah on his behalf, and this is valid for him even if he regains his health after his representative had already entered into the state of Ihram for Hajj or ‘Umrah. On the authority of al-Fadl Ibn ‘Abbas t: A woman from al-Khath’am said,“O Messenger of Allah, the obligation from Allah to perform Hajj came upon my father while he is very old and incapable of riding a camel.”
The Prophet ﷺ said:“Perform Hajj on his behalf.”
[ Source: At-Tirmidhi.]There are numerous conditions stipulated for the person performing Hajj on behalf of another:1- He must have met the aforementioned conditions of Hajj.2- He must have first performed Hajj for himself. When a person performs Hajj on behalf of another, but has not performed it for himself, such a Hajj on behalf of another person is not valid; thus the Hajj he performed for the other person then becomes for him, and it is considered as a valid Hajj for him in Islam. Evidence for this is what was confirmed on the authority of Ibn ‘Abbas t: The Prophet ﷺ heard a man saying;“Labbayka on behalf of Shubruma,” the Prophet ﷺ asked: “Who is Shubruma?” He replied: “A brother or a relative of mine.” The Prophet then asked: “Have you performed Hajj for yourself?” He replied: “No.” So the Prophet ﷺ said: “Perform Hajj for yourself, then perform (Hajj) on behalf of Shubruma.”
[ Source: Abu Dawud.]
Source: islamkingdom