(25) باب لُبْسِ الْحَرِيرِ، وَافْتِرَاشِهِ لِلرِّجَالِ، وَقَدْرِ مَا يَجُوزُ مِنْهُ
Narrated Abu `Uthman:
While we were at Adharbijan, `Umar wrote to us: 'Allah's Messenger (ﷺ) forbade wearing silk except this much. Then the Prophet (ﷺ) approximated his two fingers (index and middle fingers) (to illustrate that) to us.' Zuhair (the sub-narrator) raised up his middle and index fingers.
Reference: Sahih al-Bukhari 5829
In-book reference: Book 77, Hadith 46
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 7, Book 72, Hadith 719