A letter from Umar reached us while we were in Adharbayjan with Utba bin Farqad, or in Sham. It read, "To proceed, the Messenger of Allah ﷺ forbade silk except for this much," indicating two fingers.Abu Uthman said, "We had no doubt that he meant the embroidered borders."
حدثنا محمد بن جعفر حدثنا شعبة وحجاج قال حدثني شعبة عن قتادة قال سمعت
جاءنا كتاب عمر ونحن بأذربيجان مع عتبة بن فرقد أو بالشام أما بعد فإن رسول الله ﷺ نهى عن الحرير إلا هكذا أصبعين قال أبو عثمان فما عتمنا إلا أنه الأعلام
Its isnad is sahih. See also 243, 301, 345.Atamna is pronounced with a fatha on the ain and a shaddah on the ta, meaning "we delayed." He means that they did not delay in grasping what he meant and intended, and that he only specified the explicitly named things.