Bismillah.
Kitaab-ul-Hajj [Book of Pilgrimage] starts today..
Volume 2, Book 26, Number 589:
Narrated 'Abdullah bin Abbas (radiallaahu `anhu):
Al-Fadl (radiallaahu `anhu) (his brother) was riding behind Allah's Apostle (sallallaahu `alayhi wasallam) and a woman from the tribe of Khath'am came and Al-Fadl (radiallaahu `anhu) started looking at her and she started looking at him. The Prophet (sallallaahu `alayhi wasallam) turned Al-Fadl's face to the other side. The woman said, "O Allah's Apostle (sallallaahu `alayhi wasallam)! The obligation of Hajj enjoined by Allah on His devotees has become due on my father and he is old and weak, and he cannot sit firm on the Mount; may I perform Hajj on his behalf?" The Prophet (sallallaahu `alayhi wasallam) replied, "Yes, you may." That happened during the Hajj-al-Wida (of the Prophet (sallallaahu `alayhi wasallam)).
Allah says in Aal-i-`Imraan: 96-97:
﴿إِنَّ أَوَّلَ بَيْتٍ وُضِعَ لِلنَّاسِ لَلَّذِى بِبَكَّةَ مُبَارَكاً وَهُدًى لِّلْعَـلَمِينَ - فِيهِ ءَايَـتٌ بَيِّـنَـتٌ مَّقَامُ إِبْرَهِيمَ وَمَن دَخَلَهُ كَانَ ءَامِناً وَللَّهِ عَلَى النَّاسِ حِجُّ الْبَيْتِ مَنِ اسْتَطَـعَ إِلَيْهِ سَبِيلاً وَمَن كَفَرَ فَإِنَّ الله غَنِىٌّ عَنِ الْعَـلَمِينَ ﴾
(96. Verily, the first House (of worship) appointed for mankind was that at Bakkah (Makkah), full of blessing, and a guidance for Al-`Alamin (mankind and Jinn). (97. In it are manifest signs (for example), the Maqam (station) of Ibrahim; whosoever enters it, he attains security. And Hajj to the House is a duty that mankind owes to Allah, for those who are able to undertake the journey; and whoever disbelieves, then Allah stands not in need of any of the `Alamin.)
In his Tafsir, Imaam Ibn Kathir says:
Allah said,
﴿وَللَّهِ عَلَى النَّاسِ حِجُّ الْبَيْتِ مَنِ اسْتَطَـعَ إِلَيْهِ سَبِيلاً﴾
(And Hajj to the House is a duty that mankind owes to Allah, for those who are able to undertake the journey) ﴿3:97﴾.
This Ayah established the obligation of performing Hajj. There are many Hadiths that mention it as one of the pillars and fundamentals of Islam, and this is agreed upon by the Muslims. According to texts and the consensus of the scholars, it is only obligatory for the adult Muslim to perform it once during his lifetime. Imam Ahmad recorded that Abu Hurayrah said that the Messenger of Allah once gave a speech in which he said,
«أَيُّهَا النَّاسُ قَدْ فُرِضَ عَلَيْكُمُ الْحَجُّ فَحُجُّوا»
(O people! Hajj has been enjoined on you, therefore, perform Hajj.)
A man asked, "Is it every year, O Allah's Messenger'' The Prophet remained silent until the man repeated the question three times and he then said,
«لَوْ قُلْتُ: نَعَمْ لَوَجَبَتْ وَلَمَا اسْتَطَعْتُم»
(Had I said yes, it would have become an obligation and you would not have been able to fulfill it.) He said next,
«ذَرُونِي مَا تَرَكْتُكُمْ فَإِنَّمَا هَلَكَ مَنْ كَانَ قَبْلَكُمْ بِكَثْرَةِ سُؤَالِهِمْ وَاخْتِلَافِهِمْ عَلى أَنْبِيَائِهِمْ، وَإِذَا أَمَرْتُكُمْ بِشَيْءٍ فَأْتُوا مِنْهُ مَا اسْتَطَعْتُمْ، وَإِذَا نَهَيْتُكُمْ عَنْ شَيْءٍ فَدَعُوه»(Leave me as I leave you, those before you were destroyed because of their many questions and disputing with their Prophets. If I command you with something, perform it as much as you can. If I forbid something for you, then refrain from it.) Muslim recorded similarly.
There are several categories of "the ability to under take the journey''. There is the physical ability of the person himself and the ability that is related to other things as mentioned in the books of jurisprudence. Abu `Isa At-Tirmidhi recorded that Ibn `Umar said, "A man stood up and asked the Messenger of Allah , `O Messenger of Allah! Who is the pilgrim' He said, `He who has untidy hair and clothes.' Another man asked, `Which Hajj is better, O Messenger of Allah' He said, `The noisy (with supplication to Allah) and bloody (with sacrifice).' Another man asked, `What is the ability to undertake the journey, O Messenger of Allah' He said, `Having provision and a means of transportation.''' This is the narration that Ibn Majah collected. Al-Hakim narrated that Anas said that the Messenger of Allah was asked about Allah's statement,
﴿مَنِ اسْتَطَـعَ إِلَيْهِ سَبِيلاً﴾
(for those who are able to undertake the journey;) ﴿3:97﴾ "What does `able to undertake the journey' mean'' The Prophet answered, "Having sufficient provision and a means of transportation.'' Al-Hakim stated that this Hadith's chain of narration is authentic, following the guidelines of Muslim in his Sahih, but the Two Sahihs did not collect it. Ahmad recorded that Ibn `Abbas said that the Messenger of Allah said,
«مَنْ أَرَادَ الْحَجَّ فَلْيَتَعَجَّل»
(Whoever intends to perform Hajj, let him rush to perform it.) Abu Dawud also collected this Hadith.
Allah said,
﴿وَمَن كَفَرَ فَإِنَّ الله غَنِىٌّ عَنِ الْعَـلَمِينَ﴾
(...and whoever disbelieves, then Allah stands not in need of any of the `Alamin) ﴿3:97﴾.
Ibn `Abbas, Mujahid and several others commented on this Ayah, "Whoever denies the necessity of Hajj becomes disbeliever, and Allah is far Richer than to need him.'' Al-Hafiz Abu Bakr Al-Isma`ili recorded that `Umar bin Al-Khattab said, "Whoever can afford Hajj but did not perform it, there is no difference in his case if he dies while Jew or Christian.'' This has an authentic chain of narration leading to `Umar.
Taken from: http://ilookilisten.wordpress.com/2013/01/04/hajj-obligation-hadith-no-1289/