Volume 7, Book 72, Number 719:
Narrated Abu ‘Uthman:
While we were at Adharbijan, ‘Umar wrote to us: ‘Allah’s Apostle forbade wearing silk except this
much. Then the Prophet approximated his two fingers (index and middle fingers) (to illustrate that)
to us.’ Zuhair (the sub-narrator) raised up his middle and index fingers.