Abu '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.

وَحَدَّثَنَا ابْنُ أَبِي شَيْبَةَ، - وَهُوَ عُثْمَانُ - وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ الْحَنْظَلِيُّ كِلاَهُمَا عَنْ جَرِيرٍ، - وَاللَّفْظُ لإِسْحَاقَ - أَخْبَرَنَا جَرِيرٌ، عَنْ سُلَيْمَانَ التَّيْمِيِّ، عَنْ أَبِي عُثْمَانَ، قَالَ كُنَّا مَعَ عُتْبَةَ بْنِ فَرْقَدٍ فَجَاءَنَا كِتَابُ عُمَرَ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏

‏ لاَ يَلْبَسُ الْحَرِيرَ إِلاَّ مَنْ لَيْسَ لَهُ مِنْهُ شَىْءٌ فِي الآخِرَةِ إِلاَّ هَكَذَا ‏

‏ ‏.‏ وَقَالَ أَبُو عُثْمَانَ بِإِصْبَعَيْهِ اللَّتَيْنِ تَلِيَانِ الإِبْهَامَ ‏.‏ فَرُئِيتُهُمَا أَزْرَارَ الطَّيَالِسَةِ حِينَ رَأَيْتُ الطَّيَالِسَةَ ‏.‏