Musnad Ahmad 5:227

'Affan narrated to us, Abu 'Awanah narrated to us, 'Abd al-A'la al-Tha'labi narrated to us, from Abu 'Abd al-Rahman al-Sulami, from 'Ali, from the Prophet, may Allah bless him and grant him peace, that he said: "Whoever lies about a dream intentionally, he will be tasked with tying a knot in a barley grain on the Day of Resurrection."