Reference: al-Muntaqaa min Fataawa Shaykh Saalih al-Fowzaan – Volume 3, Page 190, Fatwa No.291
Question: Is it permissible for a person to perform the obligation of the Hajj on behalf of someone else who is financially and physically able [to perform the Hajj himself] in exchange for money?
Response: Whoever is able to perform the obligation of the Hajj himself, then it is not permissible for him to appoint someone else to perform the Hajj on his behalf, and he will not be rewarded for it [by Allaah] if he does so.
As for the one who is unable to perform the Hajj himself due to a condition which permanently prevents him from doing so, then it is permissible for him to appoint someone else to perform the Hajj on his behalf.
And there is no harm in him taking money [for performing the Hajj] if he intends by it to use it for the Hajj, and not intending [to seek] any financial enjoyment (benefit) [by undertaking the performance of the Hajj]. And we have a rule which some of the scholars use which has been extracted from the authentic evidences, that being:
Whoever [makes the intention to] perform the Hajj to seek financial gain, then he should not perform the Hajj. And whoever takes money in order to perform the Hajj, then he should [go ahead and] perform the Hajj. [Majmoo’ al-Fataawa of Ibn Taymiyyah – volume 26, page 19]
…and the meaning of this is, whoever uses money as a means to perform the Hajj, then there is no harm in that, and (but) whoever uses the [performance of the] Hajj as a means to earn money then that is not permissible.