Sahih al-Bukhari 56
صحيح البخاري#56SahihNarrated Sa'd bin Abi Waqqas: Allah's Messenger (ﷺ) said, "You will be rewarded for whatever you spend for Allah's sake even if it were a morsel which you put in your wife's mouth
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: 2:49