Sunan Abi Dawud 4003
سنن أبي داود#4003SahihNarrated 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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih Lighairihi
Zubair Ali ZaiSahih
In-book reference: 32:35