Musnad Ahmad 5:506

Abdullah narrated to us, he said: And Khalaf ibn Hisham al-Bazzar narrated to us, Abu 'Awanah narrated to us, from 'Abd al-A'la, from Abu 'Abd al-Rahman, from 'Ali, from the Prophet, peace and blessings of Allah be upon him, who said: "Whoever lies about his eyes shall be tasked on the Day of Resurrection to tie a knot between the two ends of a barley grain."