Narrated Ibn al-Asqa':The Prophet (ﷺ) came to them in the swelling place of immigrants and a man asked him: Which is the greatest verse of the Qur'an ? The Prophet (ﷺ) replied: Allah, there is no god but He - the Living, the Self-Subsisting Eternal. No slumber can seize Him nor sleep

English translation · Sunan Abu Dawud