The case of the obligation of Hajj was like the obligation of other Islamic forms of worship which were legislated gradually. Allah first ordered the Muslims to complete the rituals of Hajj and Umrah in His saying, {Perform Hajj and Umrah (lesser pilgrimage) for Allah} [Surah Al-Baqarah: 196], which was revealed at Al-Hudaybiyah in 6 A.H. Then the order indicating the obligation of Hajj was revealed in Allah’s saying, {Hajj to the House is a duty owed to Allah by all mankind—for those who can find a way to do it} [Surah Al-Imran: 97], which was revealed during the year of the delegations, at the end of 9 A.H. [see: Zaad Al-Maad (Provisions for the Hereafter) by Ibn Al-Qayyim].
Ali ibn Abu Talib (may Allah be pleased with him) related the response of the Companions when this verse, {Hajj to the House is a duty owed to Allah by all mankind} [Surah Al-Imran: 97], was revealed. <The Companions asked the Messenger of Allah (peace be upon him), ‘Is it for every year?’ But the Messenger of Allah (peace be upon him) kept quiet. So they asked again, ‘Is it for every year?’ The Messenger of Allah (peace be upon him) still kept quiet. Then they said a third time, ‘Is it for every year?’ The Messenger of Allah (peace be upon him) replied, ‘No, and if I had said yes, it would have been obligatory.’ So Allah revealed, {Oh you who have believed, do not ask about things which, if they are shown to you, will distress you....} to the end of the verse> [related by Ahmed].
Moreover, Abu Hurayrah (may Allah be pleasedwith him) narrated about the obligation of Hajj. He said that the Messenger of Allah gave them a sermon in which he said, <‘Oh people, Allah has made Hajj obligatory on you, so perform Hajj.’ A man said, ‘Is it every year, Oh Messenger of Allah?’ So the Messenger of Allah (peace be upon him) kept quiet until the man asked three times. The Messenger of Allah (peace be upon him) then said, ‘If I had replied yes, it would be obligatory, and you would not be able to do it.’ Then he said, ‘Leave me (and don’t ask about what I have not mentioned, just take) what I have left for you, for truly, those before you were ruined because of them asking many questions and because of their disagreeing with their Prophets. If I order you to do something, fulfill it as much as you can; and if I prohibit something for you, leave it’> [related by Muslim].
In this way, the Messenger of Allah (peace be upon him) firmly established a great Islamic principle, which is not to ask or search for something which the Shari’ah has not mentioned due to it taking into consideration the circumstances of those it addresses. Strictness is not a character which brings good for the person who is strict.