اللَّهُمَّ اجْعَلْنِي مِنَ التَّوَّابِينَ وَاجْعَلْنِي مِنَ الْمُتَطَهِّرِينَ
Allahummaj'alni minat-tawwabina waj'alni minal-mutatahhirin
O Allah, make me among those who repent and make me among those who purify themselves.
Said after wudu, but also appropriate after prayer. Two categories of people: the tawwabin (those who constantly return to Allah in repentance) and the mutatahhirin (those who constantly purify themselves — both physically and spiritually). These are ongoing states, not one-time achievements. You do not repent once; you become a person who repents. The du'a asks for identity transformation, not just forgiveness.
Related Du'as
أَسْتَغْفِرُ اللَّهَ أَسْتَغْفِرُ اللَّهَ أَسْتَغْفِرُ اللَّهَ اللَّهُمَّ أَنْتَ السَّلَامُ وَمِنْكَ السَّلَامُ تَبَارَكْتَ يَا ذَا الْجَلَالِ وَالْإِكْرَامِ
I seek Allah's forgiveness (three times). O Allah, You are Peace and from You is peace. Blessed are You, O Owner of Majesty and Honor.
Sahihاللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنَ الْجُبْنِ وَأَعُوذُ بِكَ مِنَ الْبُخْلِ وَأَعُوذُ بِكَ مِنْ أَنْ أُرَدَّ إِلَى أَرْذَلِ الْعُمُرِ وَأَعُوذُ بِكَ مِنْ فِتْنَةِ الدُّنْيَا وَعَذَابِ الْقَبْرِ
O Allah, I seek refuge in You from cowardice, from miserliness, from being returned to the most decrepit old age, and I seek refuge in You from the trials of this world and the punishment of the grave.
Sahihلَا إِلَٰهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيكَ لَهُ لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ، اللَّهُمَّ لَا مَانِعَ لِمَا أَعْطَيْتَ وَلَا مُعْطِيَ لِمَا مَنَعْتَ وَلَا يَنْفَعُ ذَا الْجَدِّ مِنْكَ الْجَدُّ
There is no deity except Allah, alone without partner. His is the dominion and His is the praise, and He is over all things capable. O Allah, none can withhold what You have given, and none can give what You have withheld, and no wealth or might can benefit anyone against You.
Sahihأَسْتَغْفِرُ اللَّهَ أَسْتَغْفِرُ اللَّهَ أَسْتَغْفِرُ اللَّهَ
I seek Allah's forgiveness (three times).
Sahih