Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) addressed the people and said: "Indeed, Allah has made Hajj obligatory upon you." So a man said, "O Messenger of Allah, is it obligatory every year?" The Prophet (peace and blessings be upon him) did not answer him until he repeated the same question three times. Then the Messenger of Allah (peace and blessings be upon him) said: "If I had said yes, it would have become obligatory, and if it had become obligatory, you would not have been able to do it." And the Prophet (peace and blessings be upon him) said: "Leave me as long as I leave you (do not ask unnecessary questions), for those before you were destroyed only because they asked too many questions of their prophets and differed with them in many matters. Therefore, whatever I command you, do it to the best of your ability, and whatever I forbid you from, abstain from it." The narrator says that then this verse was revealed «‏‏‏‏لَا تَسْأَلُوا عَنْ أَشْيَاءَ إِن تُبْدَ لَكُمْ تَسُؤْكُمْ» ‏‏‏‏ [ سورة المائدة: 101] "(O you who believe) do not ask about things which, if made plain to you, may cause you trouble."