A letter from Umar reached us while we were with Utba bin Farqad in Azerbaijan, stating that the Messenger of Allah ﷺ forbade silk except for this much, and he pointed with his two fingers next to the thumb. He said, "As far as we understood, he meant the embroidered borders."
حدثنا آدم حدثنا شعبة حدثنا قتادة قال سمعت
أتانا كتاب عمر ونحن مع عتبة بن فرقد بأذربيجان أن رسول الله ﷺ نهى عن الحرير إلا هكذا وأشار بإصبعيه اللتين تليان الإبهام قال فيما علمنا أنه يعني الأعلام
Both of them agreed on including the hadith of Abu Uthman, who said, "Umar wrote to us regarding silk, except for the width of two fingers."Abu Uthman did not hear this from Umar directly, since Umar had written it to him, and this serves as evidence for accepting ijazah.