اللَّهُمَّ إِنِّي أَسْأَلُكَ بِأَنِّي أَشْهَدُ أَنَّكَ أَنْتَ اللَّهُ لَا إِلَهَ إِلَّا أَنْتَ، الأَحَدُ الصَّمَدُ الَّذِي لَمْ يَلِدْ وَلَمْ يُولَدْ، وَلَمْ يَكُنْ لَهُ كُفُواً أَحَدٌ

O Allāh, I ask You, as I bear witness that You are Allāh, none has the right to be worshiped except You, The One, al-Ṣamad Who begets not nor was He begotten and there is none like unto Him.

Reference: Abū Dāwud (#1493, 2/62), al-Tirmidhī (#3475, 5/515), Ibn Mājah (#3857, 2/1267) and Aḥmad (5/360). Also see Ṣaḥīḥ Ibn Mājah (2/329) and Ṣaḥīḥ al-Tirmidhī (3/163).