Sayyiduna Ali (may Allah be pleased with him) says that when this verse was revealed: {وَلِلّٰہِ عَلَی النَّاسِ حِجُّ الْبَیْتِ مَنِ اسْتطَاعَ إِلَیْہِ سَبِیْلًا} (Surah Aal-e-Imran: 97), meaning: Whoever has the ability to reach the House of Allah, Hajj to the House of Allah is obligatory upon him. The companions submitted: O Messenger of Allah! Is Hajj obligatory every year? The Prophet (peace and blessings be upon him) remained silent. They asked again: Is it obligatory every year? The Prophet (peace and blessings be upon him) remained silent. They asked a third time: Is this act of worship obligatory every year? The Prophet (peace and blessings be upon him) said: No, and if I had said yes, then Hajj would have become obligatory upon you every year. Then Allah Almighty revealed this verse: {یَا أَیُّہَا الَّذِیْنَ آمَنُوْا لَا تَسْأَلُوْا عَنْ أَشْیَائَ إِنْ تُبْدَ لَکُمْ تَسُؤْکُمْ} (Surah Al-Ma'idah: 101), meaning: O you who believe! Do not ask about things which, if made plain to you, may cause you trouble.