The time in which Hajj was made obligatory

Issue: When was Hajj made obligatory?We say: Hajj was made obligatory in the ninth year of the Hijrah. Before that, it was not made obligatory. The wisdom behind this—Allah knows best—is that before the ninth year, the House was under the authority of the polytheists. This is because Makkah was conquered in the eighth year of the Hijrah, and the Prophet (peace and blessings be upon him) remained there after the conquest until the end of Ramadan and the beginning of Shawwal. Then he fought Thaqif, and the fighting did not end until the middle of Dhul-Qa'dah. Then Hajj was made obligatory in the ninth year. This is the stronger opinion among the scholars' views.And if some of them say: It was made obligatory in the sixth year, based on the saying of the Exalted: [al-Baqarah: 196] But this opinion is weak because the verse commands the completion of the pilgrimage, not its initiation, and the discussion here concerns the initial obligation.