Sahih Muslim Book 24, Hadith Number 5153.

Chapter : The use of gold and silver vessels to forbidden to men and women and it is also prohibited to drink in them.

Abu ‘Uthman reported: While we were with ‘Utba b. Farqad there came a letter of ‘Umar (containing the instructions) that Allah’s Messenger (may peace be upon him) had said: None should wear silk (with the exception of so much) but he will have nothing of it in the Hereafter. Abu ‘Uthman said: To the extent of two fingers which are close to the thumb, and I was shown the (silk) borders of the Tayalisa mantle (which were about two fingers in breadth and I saw them.