Musnad Ahmad 27:1261

'Abd al-Samad narrated to us, 'Abd al-Rahman ibn 'Abd Allah ibn Dinar, the freed slave of Ibn 'Umar, narrated to us, from his father, from Ibn 'Umar, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, among the most grievous of lies is for a man to show his eyes in a dream what they have not seen."