Sahih al-Bukhari 6346
صحيح البخاري#6346SahihNarrated Ibn `Abbas:Allah's Messenger (ﷺ) used to say at a time of distress, "La ilaha illal-lahu Rabbul-l-'arsh il-'azim, La ilaha illallahu Rabbu-s-samawati wa Rabbu-l-ard, Rabbu-l-'arsh-il-Karim
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 80:43