Sahih al-Bukhari 5917
صحيح البخاري#5917SahihNarrated Ibn `Abbas:The Prophet (ﷺ) used to copy the people of the Scriptures in matters in which there was no order from Allah. The people of the Scripture used to let their hair hang down while the pagans used to part their hair. So the Prophet (ﷺ) let his hair hang down first, but later on he parted it
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: 77:132