Oneness, Uniqueness of Allah (Tawheed) — Hadith #7426

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)

لاَ إِلَهَ إِلاَّ اللَّهُ الْعَلِيمُ الْحَلِيمُ لاَ إِلَهَ إِلاَّ اللَّهُ رَبُّ الْعَرْشِ الْعَظِيمِ لاَ إِلَهَ إِلاَّ اللَّهُ رَبُّ السَّمَوَاتِ وَرَبُّ الأَرْضِ رَبُّ الْعَرْشِ الْكَرِيمِ ‏"

See also hadith 356.