The Essence
Ad-Daarr is the One who brings about harm or distress. However, this harm is never meaningless; it is always perfectly balanced by His wisdom to test, purify, or redirect His servants to the right path.
In the Quran
وَإِنْ يَمْسَسْكَ اللَّهُ بِضُرٍّ فَلَا كَاشِفَ لَهُ إِلَّا هُوَ
"And if Allah should touch you with adversity (Durr), there is no remover of it except Him. (Surah Al-An'am 6:17)"
In Your Duas
أَعُوذُ بِكَلِمَاتِ اللَّهِ التَّامَّاتِ مِنْ شَرِّ مَا خَلَقَ
"I seek refuge in the perfect words of Allah from the evil of that which He has created."
— Sahih Muslim 2708