اللَّهُمَّ اجْعَلْنِي مِنَ التَّوَّابِينَ وَاجْعَلْنِي مِنَ الْمُتَطَهِّرِينَ
Allahumma-j'alni minat-tawwabina waj'alni minal-mutatahhirin
O Allah, mach mich zu einem von denen, die bereuen, und mach mich zu einem von denen, die sich reinigen.
Say after completing wudu, following the shahada
This dua asks Allah to make you among those who constantly seek forgiveness and purification.