The Prophet (ﷺ) heard a person praying saying -
اَللَّهُمَّ إِنِّي أَسْأَلُكَ بِأَنَّ أَشْهَدُ أَنَّكَ أَنْتَ اللَّهُ لَا إِلَهَ إِلَّا أَنْتَ الْأَحَدُ الصَّمَدُ الَّذِيْ لَمْ يَلِدْ وَلَمْ يُوْلَدْ وَلَمْ يَكُنْ لَهُ كُفُوًا أَحَدٌ
Pronunciation
Allaahumma inni as-aluka bi anna ash-hadu annaka antallahu laa ilaaha illaa antal a'hadus samadulladhi lam yalid wa lam yulad wa lam yakun lahu kufuwan a'had
Meaning
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. Then the Prophet (ﷺ) said, You have supplicated Allah using His Greatest Name, when asked with this name He gives, and when supplicated by this name he answers.
Source: Sahih (Albani). Nasai: 1300
Read the hadith
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا خَلَفُ بْنُ خَلِيفَةَ، عَنْ حَفْصِ بْنِ أَخِي، أَنَسٍ عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ كُنْتُ مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم جَالِسًا - يَعْنِي - وَرَجُلٌ قَائِمٌ يُصَلِّي فَلَمَّا رَكَعَ وَسَجَدَ وَتَشَهَّدَ دَعَا فَقَالَ فِي دُعَائِهِ اللَّهُمَّ إِنِّي أَسْأَلُكَ بِأَنَّ لَكَ الْحَمْدَ لاَ إِلَهَ إِلاَّ أَنْتَ الْمَنَّانُ بَدِيعُ السَّمَوَاتِ وَالأَرْضِ يَا ذَا الْجَلاَلِ وَالإِكْرَامِ يَا حَىُّ يَا قَيُّومُ إِنِّي أَسْأَلُكَ . فَقَالَ النَّبِيُّ صلى الله عليه وسلم لأَصْحَابِهِ " تَدْرُونَ بِمَا دَعَا " . قَالُوا اللَّهُ وَرَسُولُهُ أَعْلَمُ . قَالَ " وَالَّذِي نَفْسِي بِيَدِهِ لَقَدْ دَعَا اللَّهَ بِاسْمِهِ الْعَظِيمِ الَّذِي إِذَا دُعِيَ بِهِ أَجَابَ وَإِذَا سُئِلَ بِهِ أَعْطَى " .
It was narrated that Anas bin Malik said: "I was sitting with the Messenger of Allah (ﷺ) and a man was standing and praying. When he bowed, prostrated and recited the tashahhud, he supplicated, and in his supplication he said: "Allahumma inni as'aluka bi-anna lakal-hamd, lailaha illa ant, al-mannanu badi'us-samawati wal-ard, ya dhal-jalali wal-ikram! Ya hayyu ya qayyum! Inni as'aluka. (O Allah, indeed I ask You since all praise is due to You, there is none worthy of worship but You, the Bestower, the Creator of the heavens and earth, O Possessor of majesty and honor, O Ever-living, O-Eternal, I ask of You.)' The Prophet (ﷺ) said: 'Do you know what he has supplicated with?' They said: "Allah (SWT) and His Messenger know best." He said: 'By the One in Whose Hand is my soul, he called upon Allah by His greatest Name, which, if He is called by it, He responds, and if He is asked by it, He gives.'" Sunan an-Nasa'i 1300 [Sahih (Albani). Nasai: 1300]
Duas from IslamicAPI's Masnun Dua dataset (based on the Quran, hadith, Hisnul Muslim and Rahe Belayat). See the dataset