اللَّهُمَّ إِنِّي أَسْأَلُكَ يَا اللَّهُ بِأَنَّكَ الْوَاحِدُ الأَحَدُ الصَّمَدُ، الَّذِي لَمْ يَلِدْ وَلَمْ يُولَدْ، وَلَمْ يَكُنْ لَهُ كُفُواً أَحَدٌ، أَنْ تَغْفِرَ لِي ذُنُوبِي، إِنَّكَ أَنْتَ الْغَفُورُ الرَّحِيمُ

O Allāh, I ask You O Allāh—as You are The One, The Only, al-Ṣamad, The One who begets not, nor was He begotten and there is none like unto Him—that You forgive me my sins for verily You are The Oft-Forgiving, Most-Merciful.

Reference: Al-Nasāʾī (3/52) and Aḥmad (4/238). Al-Albānī authenticated it in Ṣaḥīḥ al-Nasāʾī (1/280).