The Mind

16. The insane, even if the insanity was periodical – i.e. insanity appears on certain occasions – is not obliged to the Hajj, unless he was mostatee’ and able to perform most of the rites of the Hajj – including the fundamental rites of the Hajj – in his state of sanity.  In that case he is obliged to perform the Hajj.  The same ruling applies to an individual who is in a state of unconsciousness.
Freedom

17. The slave – male or female – is not obliged to the Hajj even if s/he was mostatee’ and had the permission of the master.  If with the permission of the master, his mostahab Hajj is correct, but this would not qualify as Hajjat-al-Islam.  If they were freed and were mostatee’ they would then be obliged to the Hajjat-al-Islam.
Freedom of passage

18. One of the conditions of the obligation of the Hajj is the freedom of the passage, and absence of hindrance en route to the Hajj.  If there were a danger threatening the life of the individual, his family or his assets and possessions, he would not be obliged to the Hajj.  Similarly if there was a religious prohibition, such as if [the performance of] the Hajj would result in abandoning a more important obligation such as a mandatory jihad [which the individual is liable to], or committing a disobedience the repercussion of which is greater than the outcome of the Hajj, then the Hajj is not obligatory upon him.
19. One of the conditions of the obligation of the Hajj is the availability of enough time to perform the rites of the Hajj.  If one met all the criteria for the Hajj at a time when he would not be able to get there in time, or he would manage to get there but with great difficulty that is normally unbearable, then the Hajj is not obligatory upon him.

Physical ability

20. Physical ability is one of the criteria of the obligation of the Hajj.  Thus if one was ill, or had lost a limb, or too old such that he would not be able to perform the Hajj himself, it is obligatory for him to perform the Hajj by proxy, i.e. to appoint someone else to perform the Hajj on his behalf, if he has met other criteria required for the obligation of the Hajj.
21. The individual who was financially able, if he was also physically able, it would be obligatory for him to perform the Hajj himself, and it would not be sufficient if someone else performs the Hajj on his behalf, whether voluntarily or by hire.  In the case of a mostahab Hajj, however, if someone performs the Hajj on his behalf, it would be correct.