Musnad Ahmad 2:170

Yahya narrated to us, from Shu'bah, Abu Dhubyan narrated to me: I heard Abdullah ibn al-Zubayr saying: Do not let your women wear silk, for I heard Umar narrating from the Prophet, may Allah bless him and grant him peace, that he said: "Whoever wears silk in this world shall not wear it in the Hereafter." And Abdullah ibn al-Zubayr said from himself: And whoever does not wear it in the Hereafter shall not enter Paradise. Allah the Exalted said: {And their garment therein will be silk}.