Musnad Ahmad 25:1483

Waki’ narrated to us, al-Mas’udi narrated to us, from Ibn Khuthaym, from Sa’id ibn Jubayr, from Ibn Abbas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The best of your garments is white; so wear them and shroud your dead in them. And the best of your kohl is antimony (ithmid)."