Abu Dawud Book 2, Hadith Number 1490.
Chapter : Supplications.
Narated By Anas ibn Malik : I was sitting with the Apostle of Allah (PBUH) 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 (PBUH) 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.