Sahih al-Bukhari 4208
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.‏