It is narrated from Sayyiduna Ali (may Allah be pleased with him) that when this verse was revealed {وَلِلّٰہِ عَلَی النَّاسِ حِجُّ الْبَیْتِ مَنِ اسْتَطَاعَ إِلَیْہِ سَبِیلًا} … Pilgrimage to the House is a duty owed to Allah by all people who can find a way to do it. The people said: O Messenger of Allah! Is Hajj obligatory every year? The Prophet (peace and blessings be upon him) remained silent. They asked again: Is Hajj obligatory every year? The Prophet (peace and blessings be upon him) said: No, and if I had said yes, it would have become obligatory every year. Then Allah the Exalted revealed this verse: {یٰٓاَیُّھَا الَّذِیْنَ اٰمَنُوْا لَا تَسْئــَـلُوْا عَنْ اَشْیَاء َ اِنْ تُبْدَ لَکُمْ تَسُؤْکُمْ وَاِنْ تَسْئــَـلُوْا عَنْہَا حِیْنَیُنَزَّلُ الْقُرْاٰنُ تُبْدَ لَکُمْ عَفَا اللّٰہُ عَنْہَا وَاللّٰہُ غَفُوْرٌ حَلِیْمٌ۔} … O you who believe! Do not ask about things which, if made plain to you, may cause you trouble. But if you ask about them while the Qur’an is being revealed, they will be made plain to you. Allah has pardoned that, and Allah is Most Forgiving, Most Forbearing.