(22) بَابُ: {وَكَانَ عَرْشُهُ عَلَى الْمَاءِ}، {وَهُوَ رَبُّ الْعَرْشِ الْعَظِيمِ}
Narrated Ibn `Abbas:
The Prophet (ﷺ) used to say at the time of difficulty, 'La ilaha il-lallah Al-`Alimul-Halim. La-ilaha illallah Rabul- Arsh-al-Azim, La ilaha-il-lallah Rabus-Samawati Rab-ul-Ard; wa Rab-ul-Arsh Al- Karim.' (See Hadith No. 356 and 357, Vol. 8)
Reference: Sahih al-Bukhari 7426
In-book reference: Book 97, Hadith 54
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 9, Book 93, Hadith 523