Sahih al-Bukhari 534
صحيح البخاري#534SahihNarrated Abu Huraira and `Abdullah bin `Umar:Allah's Messenger (ﷺ) said, "If it is very hot, then pray the Zuhr prayer when it becomes (a bit) cooler, as the severity of the heat is from the raging of the Hell-fire
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 9:12