Abu Dawud
Dialects And Readings Of The Quran
Book Number: 025 / Hadith Number: 3992
Narated By Ibn al-Asqa' : The Prophet (pbuh) came to them in the dwelling place of the immigrants and a man asked him: Which is the greatest verse of the Qur'an? The Prophet (pbuh) replied: "Allah, there is no god but He - the Living, the Self-Subsisting Eternal. No slumber can seize Him nor sleep."(Quran ii 255)