All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Allah, the Most High, has mandated Hajj and Umrah once in a Muslim person's lifetime. If a person is unable to perform Hajj or Umrah due to an illness that is not expected to be cured or due to old age, it is permissible for them to appoint someone to perform these acts on their behalf. This practice is called "Al-Inabah" (delegation).
The Shafi'i scholar Al-Sharwani said: "It is permissible for the one who is unable perform mandatory Hajj and Umrah due to illness or old age to appoint a proxy to perform these acts on their behalf, and this is even obligatory. In the case of mandatory Hajj, delegation on behalf of a dead person is absolutely permissible. In the case of voluntary Hajj, delegation is allowed if the person making the delegation specifies it in their will. However, a person who is physically capable and financially able to perform Hajj or Umrah is not allowed to delegate the performance of these acts to another." {Hasheyat Al-Sharwani Ala Tohfat Al-Mohtajj, Vol.7, Page 94}.
The "Ma'zoob" is someone who is physically unable to perform Hajj themselves due to a condition for which there is no expectation of recovery, such as old age, chronic illness, or disability, or because they are elderly and unable to withstand the hardships of the journey without excessive difficulty. {Al-Majmou` Shareh Al-Mohazab, Vol.7, Page 94}.
Since such individuals aren`t able to perform Hajj or Umrah themselves, it is allowed for them to delegate someone to perform these acts on their behalf if the conditions for delegation are met. Moreover, it is conditioned to obtain the consent of these individuals in case of Hajj and Umrah because they are alive as well as have free will and choice. Al- Nawawi(May Allah have mercy on him) said: "Performing Hajj on behalf of the person who is physically unable to perform it doesn`t avail without their consent…..This is because Hajj requires having intention and they have the capacity to give the permission for delegating someone to perform Hajj on their behalf."
In addition, there is no sin in performing Umrah with the intention of seeking recovery. Seeking recovery through acts of worship, such as Umrah, is a form of supplication (dua), and it is recommended for a Muslim to combine righteous deeds with their prayers.
In conclusion, it is obligatory for the person who is required to perform Hajj or Umrah, and who initially had the capability but later becomes incapable due to valid reasons such as illness, to appoint someone else to perform them on their behalf. It is also permissible for someone who is incapable to appoint another person for performing voluntary (nafilah) Hajj and Umrah. If someone wishes to perform Hajj or Umrah on behalf of an incapacitated person, they should seek the permission of the incapacitated individual to perform these acts on their behalf, and it is a condition that the person performing on behalf of another has already performed Hajj and Umrah for themselves. And Allah the Almighty knows best.