عَنْ قَتَادَةَ قَالَ سَمِعْتُ أَبَا عُثْمَانَ النَّهْدِيَّ قَالَ جَاءَنَا كِتَابُ عُمَرَ رَضِيَ اللَّهُ عَنْهُ وَنَحْنُ بِآذَرْبَيْجَانَ مَعَ عُتْبَةَ بْنِ فَرْقَدٍ أَوْ بِالشَّامِ أَمَّا بَعْدُ فَإِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ نَهَى عَنِ الْحَرِيرِ إِلَّا هَكَذَا أُصْبُعَيْنِ قَالَ أَبُو عُثْمَانَ فَمَا عَتَّمْنَا إِلَّا أَنَّهُ الْأَعْلَامُ
Abu Uthman Hindi says: A letter came to us from Sayyiduna Umar (may Allah be pleased with him); we were with Sayyiduna Utbah bin Farqad (may Allah be pleased with him) in Azerbaijan or Syria. In that letter, it was written: "As for what follows! The Noble Prophet (peace and blessings be upon him) forbade wearing silk, except for the width of two fingers." Abu Uthman says: We understood that (by two fingers it means) that stripes or marks of silk of that width are permissible.