Musnad Ahmad 2:263

Muhammad ibn Bakr narrated to us, 'Uyaynah informed us, from 'Ali ibn Zayd, who said: I arrived in Medina and entered upon Salim ibn 'Abdullah while I was wearing a silk-blend cloak. Salim said to me: "What are you doing with these clothes? I heard my father narrating from 'Umar ibn al-Khattab that the Messenger of Allah (peace and blessings of Allah be upon him) said: 'Indeed, the one who wears silk has no share [in the Hereafter].'"