Ubayy bin Ka’b RA reported: The Messenger of Allah (sallallaahu ’alayhi wa sallam) said: “Abu Mundhir! Do you know which Ayah in Allah’s Book is the greatest?” I replied: “It is ‘Allah la ilaha illa Huwal-Haiyul-Qayum (Allah! none has the right to be worshipped but He, the Ever Living…'” (2:255) Thereupon he (sallallaahu ’alayhi wa sallam) patted me in the chest and said, “Rejoice by this knowledge, O Abu Mundhir!”
(Muslim)
