Sunan Abi Dawud 2409
سنن أبي داود#2409SahihNarrated Abu al-Darda:We went out along with the Messenger of Allah (ﷺ) for some battle in intense heat, so much so that one of us placed his hand on his head, or placed his palm on his head, due to intense heat, No one of us fasted except the Messenger of Allah (ﷺ) and 'Abd Allah b. Rawahah
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Bukhari (1945) Sahih Muslim (1122)
In-book reference: 14:97