What is the criterion for identifying the pillars and obligatory acts of Hajj?

Question:
May Allah reward you, Your Eminence, father. The questioner says: How do we distinguish between the pillars and the obligatory acts, given that the Prophet (peace and blessings be upon him) said, "Learn from me your rites of Hajj"? Is there a criterion for knowing the pillars and the obligatory acts?

Answer:
Yes, there is a difference between the pillars and the obligatory acts. An obligatory act is compensated for with a sacrifice, whereas a pillar is never left off; if it is missed, it must be made up, even after some time has passed, except for standing at 'Arafah, for if that is missed, the Hajj is missed. It is necessary to distinguish between the pillars and the obligatory acts. The acts of Hajj are not all the same; some are pillars, some are obligatory, and some are recommended practices. This distinction is necessary; we do not say they are all pillars, nor do we say they are all recommended. There must be a detailed explanation of this, yes, in light of the evidence.