The Messenger of Allah ﷺ heard a man saying, "O Allah, I ask You by my testimony that You are Allah, there is no god but You, the One, the Eternal Refuge, who has not begotten and was not begotten, and to whom none is equal."The Messenger of Allah ﷺ said, "You have asked Allah by the name which, when He is asked by it, He gives, and when He is called upon by it, He answers."
أن رسول الله ﷺ سمع رجلا يقول: اللهم إني أسألك أني أشهد أنك أنت الله لا إله إلا أنت الأحد الصمد الذي لم يلد، ولم يولد، ولم يكن له كفوا أحد. فقال رسول الله ﷺ: لقد سألت الله بالاسم الذي إذا سئل به أعطى، وإذا دعى به أجاب.
Narrated by Abu Dawud (1493, 1494), Tirmidhi (3475), and Ibn Majah (3857). Ibn Hibban (891) and Hakim (1/504) both graded it sahih. All of them narrated it through Malik bin Mughul, from Abdullah bin Burayda, from his father, who related the hadith, and its chain of transmission is sahih.