Allah The Almighty has made Hajj obligatory for His slaves only once and has made it one of the five pillars of Islam. The Prophet said: "Islam is built on five (pillars)." He mentioned Hajj to the Sacred House of Allah as one of these pillars.
Allah The Almighty Says (what means): {…And [due] to Allah from the people is a pilgrimage to the House - for whoever is able to find thereto a way. But whoever disbelieves - then indeed, Allah Is Free from need of the worlds.} [Quran 3:97]
The Prophet said: "Hasten to perform Hajj for one of you does not know what will happen to him."
The Prophet also said: "Whoever intends to perform Hajj should hasten to it; for one could get sick, his mount could be lost or he could face poverty and need."
‘Umar ibn Al-Khattaab said, "I was about to send men to the different provinces to find out whoever has not performed Hajj although he is able to do so and demand that they pay the Jizyah. They are non-Muslims! They are non-Muslims!"
‘Ali ibn Abi Taalib said, "Circumambulate the House (of Allah) often before you are prevented from doing that."
Al-Hasan said, "People are still adherent to religion as long as they perform Hajj to the House and face the Qiblah (direction of prayer)."
There are great benefits in Hajj, some of which are mentioned here:
First: Hajj wipes out previous sins:
It was narrated that ‘Amr ibn Al-‘Aas said, "When Allah instilled love for Islam in my heart, I went to the Messenger of Allah and said, 'Extend your right hand, so that I may pledge allegiance to you.' He stretched his right hand, but I withdrew my hand. He said: 'What is the matter, ‘Amr?' I said, 'I wish to lay down some conditions.' He asked: 'What conditions do you wish to put forward?' I replied, 'To be granted forgiveness.' He said: 'Do you not know that (embracing) Islam wipes out what is before it (previous misdeeds), that emigration wipes out what is before it and that Hajj (pilgrimage) wipes out what is before it?'" [Muslim]
Second: Hajj purifies from sins:
Abu Hurayrah narrated that he heard the Prophet saying: "Whoever performs Hajj, during which he neither has sexual intercourse nor commits sins, he will return as sinless as a newborn child on the very day his mother delivered him." [Al-Bukhari]
Third: Hajj is one of the best righteous deeds:
Abu Hurayrah narrated that the Prophet was asked, “‘What is the best deed?’ He replied: ‘To have faith in Allah and His Messenger.’ The inquirer asked, ‘What next?’ The Prophet said: ‘To perform Jihaad for the Sake of Allah.’ The inquirer asked, ‘What next?’ The Prophet said: ‘A valid and accepted Hajj.’” [Al-Bukhari and Muslim]
Fourth: Entering Paradise is the reward of the Mabroor (accepted) Hajj:
Abu Hurayrah narrated that the Prophet said: "Two consecutive ‘Umrahs expiate sins committed in the interval between them and (entering) Paradise is the reward of the Mabroor Hajj." [Al-Bukhari and Muslim]
It was said that the Mabroor Hajj is that during which one did not sin; or it is the accepted Hajj or the Hajj intended for the Sake of Allah with neither ostentation nor showing off. The sign of a valid and accepted Hajj is that one does further acts of obedience and does not return to acts of disobedience again.
Fifth: Hajj is the best Jihaad for women, the old and the weak:
‘Aa’ishah, the Mother of the Believers said: “‘O Messenger of Allah! We see that Jihaad is the best of deeds. Should we (women) not participate in it?’ The Prophet replied: 'For you, the best Jihaad is an accepted Hajj (Mabroor Hajj).'” [Al-Bukhari and Muslim]
According to the wording of another narration, the Prophet replied: "For you, the best and most beautiful Jihaad is an accepted Hajj (Mabroor Hajj)."
It was narrated that ‘Aa’ishah upon hearing this Hadeeth, said, "I will never abandon Hajj after hearing these words from the Prophet ."
It was narrated on the authority of Abu Hurayrah that the Prophet said: "Performing Hajj and ‘Umrah is the Jihaad of the old, the weak and women." [An-Nasaa’i] [Al-Albaani: Hasan]
Sixth: Hajj and ‘Umrah wipe out poverty and sins:
It was narrated that Jaabir ibn ‘Abdullah said: "Perform Hajj and ‘Umrah continuously for they wipe out poverty and sins just as fire wipes out the filth of iron." [At-Tabaraani] [Al-Albaani: Saheeh]
Seventh: The expense of Hajj is doubled seven hundred times:
Buraydah narrated that the Prophet said: "(The reward of) spending on Hajj is seven hundred times as (the reward of) of spending for the Sake of Allah (Jihaad)." [Ahmad] [As-Suyooti: Saheeh]
Eighth: The pilgrim's supplication is answered:
Ibn ‘Umar narrated that the Prophet said: "The fighter for the Sake of Allah and the one performing Hajj and ‘Umrah are the delegation of Allah, whom He has invited and they responded. As a reward, Allah gives them whatever they ask for." [Ibn Maajah] [Al-Albaani: Saheeh]
Ninth: The pilgrim is under the protection of Allah:
Abu Hurayrah narrated that the Prophet said: "Three (types) of people are under the protection of Allah: A man who went out to one of the Masjids of Allah, a man who went out to fight in the Cause of Allah and a man who went out for Hajj." [Abu Nu‘aym] [Al-Albaani: Saheeh]
Tenth: Rewards never stop during the entire journey:
Ibn ‘Umar narrated that the Prophet said: "When you go out of your house intending the Sacred House, with each step by your mount, Allah records a reward for you and wipes out one of your misdeeds; when you stand at ‘Arafah, Allah descends to the lowest heaven and boasts of you before the angels…Your misdeeds will be forgiven even if they are like the sand particles of ‘Aalij [a place with a lot of sand], the days of the worldly life or the drops of rain; when you throw the pebbles, this is saved for you (on the Hereafter); when you shave your head, a reward will be recorded for you with each hair that falls; when you perform Tawaaf (circumambulating the Ka‘bah), you will return as sinless as a newborn child on the very day your mother delivered you." [At-Tabaraani] [Al-Albaani: Hasan]
Eleventh: It is impermissible to abandon Hajj:
Ibn ‘Abbaas narrated that the Prophet said: "There is no abandonment of Hajj in Islam." [Al-Haakim and Ath-Thahabi: Saheeh]
So, you should hasten to perform Hajj before your death. It was narrated that ‘Umar said, "Whoever has provision and a mount and dies without performing Hajj, let him die as a Jew or a Christian." This is meant to be a warning for such a person.