Anas bin Malik reported,

I was sitting with the Messenger of Allah ﷺ while a man was standing in prayer. When he had completed his bowing, prostration, and testimony of faith, he made supplication, saying, "O Allah, I ask You by virtue of the fact that to You belongs all praise, there is no god but You, the Bestower, the Originator of the heavens and the earth, Possessor of Majesty and Honor, Ever-Living, Self-Sustaining, I ask You."The Prophet ﷺ then said to his companions, "Do you know what he supplicated with?"They replied, "Allah and His Messenger know best."He said, "By the One in whose hand is my soul, he has supplicated to Allah by His Greatest Name, which when He is called upon by it He answers, and when He is asked by it He gives."

أخبرنا قتيبة قال حدثنا خلف بن خليفة عن حفص بن أخي أنس

عن أنس بن مالك قال

كنت مع رسول الله ﷺ جالسا يعني ورجل قائم يصلي فلما ركع وسجد وتشهد دعا فقال في دعائه اللهم إني أسألك بأن لك الحمد لا إله إلا أنت المنان بديع السماوات والأرض يا ذا الجلال والإكرام يا حي يا قيوم إني أسألك فقال النبي ﷺ لأصحابه تدرون بما دعا قالوا الله ورسوله أعلم قال والذي نفسي بيده لقد دعا الله باسمه العظيم الذي إذا دعي به أجاب وإذا سئل به أعطى