Musnad Abu Ya'la al-Mawsili 130:43

'Abd al-A'la narrated to us, 'Uthman ibn 'Umar narrated to us, Shu'bah narrated to us, 'Abd al-'Aziz ibn Suhayb narrated to us, from Anas ibn Malik, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Whoever wears it in the world will not wear it in the Hereafter," meaning silk.