Sahih al-Bukhari 6690
صحيح البخاري#6690SahihNarrated Ka`b bin Malik:In the last part of his narration about the three who remained behind (from the battle of Tabuk). (I said) "As a proof of my true repentance (for not joining the Holy battle of Tabuk), I shall give up all my property for the sake of Allah and His Apostle (as an expiation for that sin)." The Prophet (ﷺ) said (to me), "Keep some of your wealth, for that is better for you
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: 83:67