It was narrated that ‘Ali (رضي الله عنه) said:
When this verse `And Hajj (pilgrimage to Makkah) to the house (Ka`bah) is a duty that mankind owes to Allah, those who can afford the expenses (for one`s conveyance, provision and residence)` [Al-`Imran 3:97] was revealed, they said: O Messenger of Allah (ﷺ), is it every year? He remained silent. Then they said: Is it every year? He remained silent, Then they said: Is it every year? He said: `No, if I said yes, it would be obligatory.` Then Allah revealed the words: `O you who believe! Ask not about things which, if made plain to you, may cause you trouble` [Al-Ma’idah 5:101] up to the end of the Αyah.