Sahih Muslim 6864
صحيح مسلم#6864SahihAbu Musa reported that he (and his other companions) were climbing upon the hillock along with Allah's Messenger (ﷺ) and when any person climbed up, he pronounced (loudly):" There is no god but Allah, Allah is the Greatest." Thereupon Allah's Apostle (ﷺ) said: Verily, you are not supplicating One Who is deaf or absent. He said: Abu Musa or Abdullah b Qais, should I not direct you to the words (which form) the treasure of Paradise? I said: Allah's Messenger, what are these? He said:" There is no might and no power but that of Allah
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 48:58