اَللَّهُمَّ إِنِّي أَسْأَلُكَ بِأَنِّي أَشْهَدُ أَنَّكَ أَنْتَ اَللَّهُ لَا إِلَهَ إِلَّا أَنْتَ الْأَحَدُ الصَّمَدُ اَلَّذِي لَمْ يَلِدْ وَلَمْ يُوْلَدْ وَلَمْ يَكُنْ لَهُ كُفُوًا أَحَدٌ

Allaahumma 'innee 'as'aluka bi'anni 'ash-hadu 'annaka 'AntAllahu laa 'ilaaha 'illaa 'Antal-'Ahadus-Samadul-ladhee lam yalid wa lam youlad wa lam yakun lahu kufuwan 'Ahad

O Allah, I ask You, by the fact that I bear witness that You are Allah. There is none worthy of worship but You, the Only God, Independent of creation, Who was not begotten and begets not , and none is equal to Him. "Buraidah (RA) said, “The Prophet (ﷺ) heard a man supplicating with this dua, So he said: ‘By the One in Whose Hand is my soul, he has asked Allah by His Greatest Name, the one which if He is called upon by it, He responds, and when He is asked by it, He gives."

Reference: Sahih. Tirmidhi: 3475