[Ruling on Delaying Ḥajj Despite Ability]

Answer—and with Allah is success: What I see, by way of sincere counsel, is that they should all perform Ḥajj, for several reasons:
1. Allah the Exalted has commanded hastening to His forgiveness: “And hasten to forgiveness from your Lord.” [Āl ʿImrān:133]
2. Many scholars have said that obligations are to be performed immediately (ʿalā al-fawr); this is the adopted view of the madhhab.
3. One who delays Ḥajj while able may be confronted by preoccupations, illnesses, travel restrictions, poverty, or death—thus, by delaying, depriving himself of tremendous good. The means to Ḥajj may not come together for him again before he dies. It is narrated from the Prophet—May Allah bless him and his family and grant them peace—“Perform Ḥajj before you become unable to perform Ḥajj.”
If it be said: How is the ruling for one who delays Ḥajj, though able and without excuse, while intending, determined, and resolved to perform Ḥajj the next year or after, but then dies before performing it?
It is said in reply: The time for Ḥajj relative to the legally responsible person is the span of his lifetime; there is no disagreement about this among the scholars. Whoever among the legally responsible performs Ḥajj within his lifetime has discharged what is upon him—whether that be at the outset of his life, its middle, or its end.
Accordingly: if the person is young, sound, and strong; security is stable such that he does not fear being killed; and, due to that, he judges it likely that his life will extend—then it is permissible for him to delay Ḥajj to another year.
But if he has reached the latter years of life; weakness overcomes him; and he finds illnesses and ailments recurring now and again—then it is not permissible for him to delay Ḥajj, because he cannot reasonably expect to reach the next year.
Likewise, if a youth at the beginning of his life is afflicted with serious diseases, yet is able to perform Ḥajj, it is not permissible for him to delay it—such as with some liver diseases, cancers, and the like.
Likewise, if a youth lives in a land where he fears for his life due to lack of security, chaos, and fighting—yet is able to perform Ḥajj—it is not permissible for him to delay it.
To summarize: if the person has a reasonable presumption of surviving until the following year, it is permissible [to delay]; if he does not—due to old age, illness, or fear—then it is not permissible for him to delay Ḥajj. Thus have some scholars stated.
If it be said: An elderly man—however weak and oft-sick—does not lose hope in life and longevity; indeed, it is reported: “The son of Adam grows old, and two traits grow old with him: greed and long hope.” On this basis, it would be permissible for him to delay, since he presumes survival to the next year.
It is said in reply: That is a corrupt presumption and a false hope, of no legal consideration. Were the holder of such a corrupt presumption and false hope to be counseled and reminded, the falsity of what he hopes and presumes would become apparent to him. Such a notion, then, is not considered; rather, what counts is a sound presumption and true hope—i.e., what is built on recognized causes and indications.
What prudence and due caution call for is hastening to perform Ḥajj upon capability. Scholars have differed whether unrestricted obligations are immediate or may be deferred; although Ḥajj is a time-bound obligation—its “time” being one’s lifetime—in ruling it is akin to unrestricted obligations, and the stronger view is that unrestricted commands in the Sacred Law are for immediate performance.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.1