Narrated Ibn `Abbas (RA): Allah's Messenger (ﷺ) used to say at a time of distress:

لَا إِلَهَ إِلَّا اللَّهُ الْعَظِيْمُ الْحَلِيمُ، لَا إِلَهَ إِلَّا اللَّهُ رَبُّ الْعَرْشِ الْعَظِيمِ لَا إِلَهَ إِلَّا اللَّهُ رَبُّ السَّمَاوَاتِ وَرَبُّ الْأَرْضِ وَرَبُّ الْعَرْشِ الْكَرِيمِ

Laa ilaaha illallahul 'azimul halim Laa ilaaha illaallahu Rabbul 'arshil-'azim, Laa ilaaha illaallahu Rabbu-s-samaawaati wa Rabbul ardi, wa Rabbul 'arsh-il-Karim

There is none worthy of worship but Allah the Mighty, the Forbearing. There is none worthy of worship but Allah, Lord of the Magnificent Throne. There is none worthy of worship but Allah, Lord of the heavens and Lord of the earth, and Lord of the Noble Throne.

Reference: Bukhari: 6346