The dua when feeling fear is: 'La ilaha illallahul-'Adhimul-Halim, la ilaha illallahu Rabbul-'Arshil-'Adhim, la ilaha illallahu Rabbus-samawati wa Rabbul-ardi wa Rabbul-'Arshil-Karim' — These are the words Hz. Peygamber would say during times of distress, acknowledging Allah's greatness and sovereignty.
لَا إِلَٰهَ إِلَّا اللَّهُ الْعَظِيمُ الْحَلِيمُ، لَا إِلَٰهَ إِلَّا اللَّهُ رَبُّ الْعَرْشِ الْعَظِيمِ، لَا إِلَٰهَ إِلَّا اللَّهُ رَبُّ السَّمَاوَاتِ وَرَبُّ الْأَرْضِ وَرَبُّ الْعَرْشِ الْكَرِيمِ
La ilaha illallahul-'Adhimul-Halim, la ilaha illallahu Rabbul-'Arshil-'Adhim, la ilaha illallahu Rabbus-samawati wa Rabbul-ardi wa Rabbul-'Arshil-Karim.
Meaning: There is no god but Allah, the Great, the Forbearing. There is no god but Allah, Lord of the Magnificent Throne. There is no god but Allah, Lord of the heavens, Lord of the earth, and Lord of the Noble Throne.
Source: Sahih al-Bukhari #6346These are the words of Hz. Peygamber (sallallahu aleyhi ve sellem) during his most difficult moments. By declaring Allah's greatness, sovereignty over the Throne, heavens and earth, the believer reminds the heart that the One who controls everything is their Lord. No fear can overcome the one who truly understands these words. During Hac, when crowds and unfamiliar situations may cause fear, bu dua provides comfort.
لَا إِلَٰهَ إِلَّا اللَّهُ الْعَظِيمُ الْحَلِيمُ، لَا إِلَٰهَ إِلَّا اللَّهُ رَبُّ الْعَرْشِ الْعَظِيمِ، لَا إِلَٰهَ إِلَّا اللَّهُ رَبُّ السَّمَاوَاتِ وَرَبُّ الْأَرْضِ وَرَبُّ الْعَرْشِ الْكَرِيمِ
The Prophet (peace be upon him) used to say during times of distress: 'La ilaha illallahul-'Adhimul-Halim, la ilaha illallahu Rabbul-'Arshil-'Adhim, la ilaha illallahu Rabbus-samawati wa Rabbul-ardi wa Rabbul-'Arshil-Karim.'