Sahih al-Bukhari 4906
صحيح البخاري#4906SahihNarrated Musa bin `Uqba:`Abdullah bin Al-Fadl told me that Anas bin Malik said, "I was much grieve over those who had been killed in the Battle of Al-Harra. When Zaid bin Arqarr heard of my intense grief (over the killed Ansar), he wrote a letter to me saying that he heard Allah's Messenger (ﷺ) saying, O Allah! Forgive the Ansar and the Ansar children. The subnarrator, Ibn Al-Fadl, is not sure whether the Prophet (ﷺ) also said, And their grand-children." Some of those who were present, asked Anas (about Zaid). He said, "He (Zaid) is the one about whom Allah's Messenger (ﷺ) said, 'He is the one whose sound hearing Allah testified
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: 65:426