Sahih Muslim 5413
صحيح مسلم#5413SahihAbu 'Uthman reported:While we were with 'Utba b. Farqad there came a letter of 'Umar (containing the instructions) that Allah's Messenger (ﷺ) 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)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 37:28