Allah's Messenger (ﷺ) said, "If a servant commits a sin, then performs ablution properly, then stands up and prays two rak'ats and seeks forgiveness from Allah, Allah will surely forgive him." Then he recited this verse –

وَالَّذِينَ إِذَا فَعَلُوا فَاحِشَةً أَوْ ظَلَمُوا أَنفُسَهُمْ ذَكَرُوا اللَّهَ فَاسْتَغْفَرُوا لِذُنُوبِهِمْ وَمَن يَغْفِرُ الذُّنُوبَ إِلَّا اللَّهُ وَلَمْ يُصِرُّوا عَلَىٰ مَا فَعَلُوا وَهُمْ يَعْلَمُونَ ﴿١٣٥﴾ أُولَٰئِكَ جَزَاؤُهُم مَّغْفِرَةٌ مِّن رَّبِّهِمْ وَجَنَّاتٌ تَجْرِي مِن تَحْتِهَا الْأَنْهَارُ خَالِدِينَ فِيهَا ۚ وَنِعْمَ أَجْرُ الْعَامِلِينَ ﴿١٣٦﴾

Rabbanaa laa tuzigh quloobanaa ba'da iz hadaitanaa wa hab lanaa mil-ladunka rahmah; innaka Antal-Wahhaab.

(135) And those who, when they commit an immorality or wrong themselves [by transgression], remember Allah and seek forgiveness for their sins - and who can forgive sins except Allah ? - and [who] do not persist in what they have done while they know. (136) Those - their reward is forgiveness from their Lord and gardens beneath which rivers flow [in Paradise], wherein they will abide eternally; and excellent is the reward of the [righteous] workers. (Sura Ali Imran 3:135-136)

Reference: Sahih. Abu Dawud: 1521