The Messenger of Allah ﷺ entered the mosque and saw a man who had finished his prayer, and was reciting the tashahhud saying: O Allah, I ask you, O Allah, the One, the eternally besought of all, He begetteth not, nor was He begotten, and there is none comparable unto Him, that you may forgive me my sins, you are Most Forgiving, Merciful. He (the Prophet) said: He was forgiven (repeating three times.) (Using translation from Abū Dāʾūd 985)
قَالَ دَخَلَ رَسُولُ اللَّهِ ﷺ الْمَسْجِدَ فَإِذَا هُوَ بِرَجُلٍ قَدْ صَلَّى صَلَاتَهُ وَهُوَ يَتَشَهَّدُ وَيَقُولُ اللَّهُمَّ إِنِّي أَسْأَلُكَ بِاللَّهِ الْأَحَدِ الصَّمَدِ الَّذِي لَمْ يَلِدْ وَلَمْ يُولَدْ وَلَمْ يَكُنْ لَهُ كُفُوًا أَحَدٌ أَنْ تَغْفِرَ لِي ذُنُوبِي إِنَّكَ أَنْتَ الْغَفُورُ الرَّحِيمُ فَقَالَ «قَدْ غُفِرَ لَهُ قَدْ غُفِرَ لَهُ قَدْ غُفِرَ لَهُ»