Du'a for protection from all harm

بِسْمِ اللهِ الَّذِي لَا يَضُرُّ مَعَ اسْمِهِ شَيْءٌ فِي الْأَرْضِ وَلَا فِي السَّمَاءِ، وَهُوَ السَّمِيعُ الْعَلِيمُ

Bismillahil-ladhi la yadurru ma'as-mihi shay'un fil-ardi wa la fis-sama'i, wa huwas-sami'ul-'alim

In the Name of Allah, with Whose Name there is protection against every kind of harm in the earth or in the heaven, and He is the All-Hearing and All-Knowing.

Sunan Abī Dāwūd 5088