Sahih al-Bukhari 218
صحيح البخاري#218SahihNarrated Ibn `Abbas:The Prophet (ﷺ) once passed by two graves and said, "These two persons are being tortured not for a major sin (to avoid). One of them never saved himself from being soiled with his urine, while the other used to go about with calumnies (to make enmity between friends)." The Prophet (ﷺ) then took a green leaf of a date-palm tree, split it into (pieces) and fixed one on each grave. They said, "O Allah's Apostle! Why have you done so?" He replied, "I hope that their punishment might be lessened till these (the pieces of the leaf) become dry." (See the footnote of Hadith)
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: 4:84