Upon completion of wudhu

أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيكَ لَهُ، وَأَشْهَدُ أَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ، اللَّهُمَّ اجْعَلْنِي مِنَ التَّوَّابِينَ وَاجْعَلْنِي مِنَ الْمُتَطَهِّرِينَ

Asyhadu an-laa ilaaha illallaahu wahdahuu laa syariika lah, wa-asyhadu anna Muhammadan 'abduhuu warasuuluh. Allahummaj'alnii minat tawwaabiina waj'alnii minal mutathahhiriin.

I bear witness that there is no god but Allah alone, with no partner, and I bear witness that Muhammad is His servant and His Messenger. O Allah, make me among those who repent and make me among those who purify themselves.

Sahih Muslim 234; Jami' at-Tirmidhi 55