Which Ayah in Allah's Book is the greatest

السلام عليكم و رحمة الله و بركاته بِسْمِ اللهِ الرَّحْمنِ الرَّحِيمِThe Messenger of Allah (صلى الله عليه و سلم ) 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 worshiped but He, the Ever Living..." (2:256) Thereupon he (صلى الله عليه و سلم ) patted me in the chest and said, "Rejoice by this knowledge, O Abu Mundhir!"[Muslim]
Commentary: The words cited in the Hadith occur in the beginning of Ayat-ul-Kursi (No.256 of Surat Al-Baqarah of the holy Qur'an)