Narrated Anas ibn Malik:

I was sitting with the Messenger of Allah ﷺ and a man was offering prayer. He then made supplication: O Allah, I ask Thee by virtue of the fact that praise is due to Thee, there is no deity but Thou, Who showest favour and beneficence, the Originator of the Heavens and the earth, O Lord of Majesty and Splendour, O Living One, O Eternal One.

The Prophet ﷺ then said: He has supplicated Allah using His Greatest Name, when supplicated by this name, He answers, and when asked by this name He gives.

حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ عُبَيْدِ اللَّهِ الْحَلَبِيُّ، حَدَّثَنَا خَلَفُ بْنُ خَلِيفَةَ، عَنْ حَفْصٍ، - يَعْنِي ابْنَ أَخِي أَنَسٍ - عَنْ أَنَسٍ، أَنَّهُ كَانَ مَعَ رَسُولِ اللَّهِ ﷺ جَالِسًا وَرَجُلٌ يُصَلِّي ثُمَّ دَعَا اللَّهُمَّ إِنِّي أَسْأَلُكَ بِأَنَّ لَكَ الْحَمْدَ لاَ إِلَهَ إِلاَّ أَنْتَ الْمَنَّانُ بَدِيعُ السَّمَوَاتِ وَالأَرْضِ يَا ذَا الْجَلاَلِ وَالإِكْرَامِ يَا حَىُّ يَا قَيُّومُ . فَقَالَ النَّبِيُّ ﷺ
" لَقَدْ دَعَا اللَّهَ بِاسْمِهِ الْعَظِيمِ الَّذِي إِذَا دُعِيَ بِهِ أَجَابَ وَإِذَا سُئِلَ بِهِ أَعْطَى " .