There is a difference between a person who is unable to perform Hajj due to old age and a person who is unable due to illness, because a person who is unable due to old age cannot regain youth and strength, whereas a sick person can recover by the command and mercy of Allah Almighty.

Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that Sayyiduna Fadl bin Abbas (may Allah be pleased with them both) was riding behind the Messenger of Allah (peace and blessings be upon him) when a woman from the tribe of Khath’am came to ask the Prophet a question. Sayyiduna Fadl bin Abbas (may Allah be pleased with them both) began to look at her and she also started looking at Sayyiduna Fadl bin Abbas (may Allah be pleased with them both), so the Messenger of Allah (peace and blessings be upon him) turned the face of Sayyiduna Fadl bin Abbas (may Allah be pleased with them both) to the other side with his blessed hand. She said,“O Messenger of Allah, Allah has made Hajj obligatory upon His servants, but my elderly father is not able to sit firmly on a mount. Should I perform Hajj on his behalf?”The Prophet (peace and blessings be upon him) replied,“Yes.”And this incident took place during the Farewell Pilgrimage.

The wording of the hadith in this regard is general, not detailed (that is, the hadith mentions performing Hajj on behalf of an old man, but does not mention a woman; however, Hajj can be performed on behalf of both men and women).

Imam Hasan Basri (may Allah have mercy on him) says that it has reached me that a man came to the Messenger of Allah (peace and blessings be upon him) and said: "My elderly father has accepted Islam and he has not performed Hajj, nor can he sit firmly on a mount, and if I tie him to the mount with a rope, I fear that I might kill him." So the Messenger of Allah (peace and blessings be upon him) said: "Perform Hajj on behalf of your father."

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) in a similar manner as mentioned above, with only this difference that in this narration, a questioner asked about his mother.

And the evidence that the reports I mentioned are general and not detailed as I stated is that there is nothing in those reports indicating that the Prophet, peace and blessings be upon him, asked the one whom he commanded to perform Hajj on behalf of another whether he had performed Hajj for himself or not. This report indicates that the Prophet, peace and blessings be upon him, only commanded those who had performed Hajj for themselves to perform Hajj on behalf of others, not those who had not performed Hajj for themselves.

It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) heard a man making intention for Hajj with these words: "O Allah, I am present on behalf of Shubrumah." The Prophet asked: "Who is Shubrumah?" He replied: "He is my brother or a close relative." The Prophet (peace and blessings be upon him) said: "Have you performed Hajj on your own behalf?" He said: "No." The Prophet (peace and blessings be upon him) said: "Then perform this Hajj on your own behalf, then perform it on behalf of Shubrumah." Imam Abu Bakr (may Allah have mercy on him) says that in this narration it is stated that whoever calls the Talbiyah on behalf of another person and has not performed Hajj for himself, he should perform that Hajj on his own behalf.

Sayyiduna Ibn Razin (may Allah be pleased with him) narrates that he said: O Messenger of Allah, my father is an old man who is not able to perform Hajj and Umrah or to travel. The Prophet (peace and blessings of Allah be upon him) said: "You perform Hajj and Umrah on behalf of your father."

This also proves that the vow (such as Hajj, etc.) should be fulfilled from the entire wealth of the deceased, because the Prophet (peace be upon him) likened the vow of Hajj to a debt (and a debt is paid from the whole wealth, not just one third of it).

Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that a woman made a vow to perform Hajj, then she passed away. Her brother came to the Messenger of Allah (peace be upon him) and asked about this issue. The Prophet (peace be upon him) said: "What do you think, if your sister had a debt, would you pay off her debt?" He replied, "Yes." The Prophet (peace be upon him) said: "Then fulfill Allah's debt (the vow of Hajj), for Allah's debt is more deserving of being paid."