Hadithcore
Sahih al-Bukhari, 4208
sahih

Narrated Abu `Imran:

Anas looked at the people wearing Tailsans (i.e. a special kind of head covering worn by Jews in old days). On that Anas said, "At this moment they (i.e. those people) look like the Jews of Khaibar."

حَدَّثَنَا مُحَمَّدُ بْنُ سَعِيدٍ الْخُزَاعِيُّ، حَدَّثَنَا زِيَادُ بْنُ الرَّبِيعِ، عَنْ أَبِي عِمْرَانَ، قَالَ نَظَرَ أَنَسٌ إِلَى النَّاسِ يَوْمَ الْجُمُعَةِ، فَرَأَى طَيَالِسَةً فَقَالَ كَأَنَّهُمُ السَّاعَةَ يَهُودُ خَيْبَرَ‏.‏

References2 variants
In-Book Reference
Book 64, Hadith 248
USC-MSA web (English) reference
Vol. 5, Book 59, Hadith 519 (deprecated numbering scheme)