Abu Uthman (may Allah have mercy on him) said: Sayyiduna Umar (may Allah be pleased with him) wrote to us while we were in Azerbaijan: O Utbah bin Farqad! This was not obtained by your toil, nor by the toil of your father or your mother. He said it three times, and said: Let the Muslims eat their fill in their dwellings of what you eat your fill of in your own dwelling; beware of luxury, of resembling the idolaters, and of wearing silk garments; for the Messenger of Allah (peace and blessings be upon him) "forbade wearing silk garments, except for the measure of two fingers."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الخوف / 6080