Musnad Ahmad 593:8

'Abd al-Samad narrated to us, Hisham narrated to us, from Qatadah, from Shahr, from 'Abd al-Rahman ibn Ghanam, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever adorns himself or is adorned with a piece of gold the size of a grain, he will be branded with it on the Day of Resurrection."