Sahih al-Bukhari 6273
صحيح البخاري#6273SahihNarrated Abu Bakra:Allah's Messenger (ﷺ) said, "Shall I inform you of the biggest of the great sins?" They said, "Yes, O Allah's Apostle!" He said, "To join partners in worship with Allah, and to be undutiful to one's parents
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: 79:47