It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) addressed us and said: "O people, Allah Almighty has made Hajj obligatory upon you." At this, al-Aqra' bin Habis stood up and asked: O Messenger of Allah, is it (obligatory) every year? He (peace and blessings be upon him) said: "Had I said yes, it would have become obligatory (every year), and had it become obligatory, you would not have acted upon it (or: you would not have been able to act upon it). Hajj is (once in a lifetime) only once, and whoever does more than that, it is voluntary." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), and they did not record it; and Sufyan bin Husayn al-Wasiti also narrated it in the same way from al-Zuhri.