The Prophet (peace and blessings be upon him) said, “Islam is built upon five pillars: testifying that there is no true god except Allah and that Muhammad is the Messenger of Allah, performing Prayer, paying the zakah, making the pilgrimage to the Sacred House (Hajj), and fasting the month of Ramadan” (Al-Bukhari).
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states the following: In order for Hajj to be valid or proper, the following pillars as well as essentials must be fulfilled: First let me list the pillars (arkan; singular rukn) without which one misses the Hajj altogether; then we will list the essentials.
The pillars of Hajj are intention (Niyya) and ihram, standing in the plains of Arafat, performing Tawaf Al-Ifadah and the ritual of Sa`i (running) between the hills of Safa and Marwah, and, finally, shaving or trimming the hair. Although no one doubts the importance of any of the above, the above list is according to the Shafi`i School; the Hanafis, however, do not consider ihram as a pillar (rukn) but as a condition for the validity of Hajj, which is the same thing. Hanafis consider shaving or trimming hair not as a pillar but as an essential.
The essentials (wajibat) are the following:
1. Ihram at the prescribed station (miqat) or prior to reaching there. It must be done during the months of Hajj.
2. Pelting the stone pillars.
3. Sacrifice for those who perform tamattu` or qiran forms of Hajj. If they cannot afford it, they can expiate through fasting.
4. Shunning all the sinful activities and all actions and behaviour that may invalidate the Hajj.
5. Tawaf of arrival is essential according to Malikis, although no one denies its importance.
6. Salah of Tawaf is essential according to Hanafis, but others consider it a Sunnah.
7. Sa`i between the two hills is an essential according to Hanafis, which can be compensated for by sacrifice if a person misses it; but others consider it as rukn.
8. Shaving or trimming of hair is wajib according to three schools; it is rukn according to Shafi`i.
9. Farewell Tawaf is essential (wajib) according to imams Abu Hanifah, Shafi`i, and Ahmad; but it is sunnah according to Imam Malik (may Allah be pleased with them all).
10. Spending at least some time during the night in Muzdalifah while returning from Arafat before proceeding to Mina.
It should be made clear that none of the above mentioned imams consider any of the above as less important; they are only differing about the precise technicality of describing each of the above mentioned rites.
Finally, while the form of Hajj is important, the spirit and soul of Hajj are also important. They are related to focusing on the inner aspects of Hajj. At the heart of Hajj is remembrance of Allah and readiness to respond to His call, and fulfilling it with a spirit of utter love and devotion.