What are the matters that make Hajj obligatory other than the obligatory duty?

The questioner : May Allah reward you, O honorable Shaykh. What are the matters that make a Muslim obligated to perform Hajj as an obligation, other than the obligatory duty?

The Shaykh : A vow. If a person makes a vow that is a vow of devotion, he must perform Hajj, based on the saying of the Prophet (peace and blessings be upon him): Hajj is obedience to Allah and His Messenger. So if he vows to perform Hajj, he must perform it. When we say "a vow of devotion," we mean to distinguish it from a vow made in anger or stubbornness, which is intended to prevent something, urge something, affirm something, or deny something. This is clarified by an example. For instance, if he says, "If Allah heals my sick person, I owe Allah that I will perform Hajj this year" or "I will perform Hajj," this is called a vow of devotion because it is a vow in exchange for a blessing, and thus it is an act of gratitude. However, if he says, "If I speak to so-and-so, I vow to Allah that I will perform Hajj every year," he is not required to fulfill it, because he did not intend to draw near to Allah through Hajj; rather, he intended to burden himself so that he would refrain from what he vowed against. The important point is that Hajj becomes obligatory by a vow. It also becomes obligatory if one begins it, even if it was voluntary, based on the saying of Allah the Exalted: This verse was revealed before Hajj became obligatory, because it was revealed at al-Hudaybiyyah in the sixth year of the Hijrah, and the obligation of Hajj was established in the ninth year. Accordingly, Hajj becomes obligatory for two reasons: by beginning it and by a vow. As for the obligatory duty, that is evident.