He asked 'Abdullah bin 'Abbas about wearing silk. He said: "Ask 'Aishah." "So I asked 'Aishah and she said: 'Ask 'Abdullah bin 'Umar.' So I asked Ibn 'Umar and he said: 'Abu Hafs told me, that the Messenger of Allah said: "Whoever wears silk in this world will have no share in the Hereafter."
Sunan an-Nasa'i Book 48, Hadith 267