Sahih Muslim | Book 24 | Hadith Number 5154

Narrated by Qatada
Qatada reported: I heard Abe 'Uthman al-Nahdi as saying: There came to us a letter of 'Umar as we were in Adharba'ijan or in Syria in the company of 'Utba b. Farqad (and the letter ran thus): After (usual praise and glorification of Allah) it is stated that Allah's Messenger (may peace be upon him) has forbidden the use of silk but to the extent of these two fingers, and Abu Uthman said: We at once understood by these words that he meant (silk) patterns on (the cloth).