Musannaf Ibn Abi Shayba 23:186

Ahmad ibn Abdullah narrated to us, from Layth ibn Sa'd, from Abu al-Zubayr, from Jabir, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "If one of you sees a vision that he dislikes, let him spit to his left three times, and let him seek refuge in Allah from the Shaytan three times, and let him turn over from the side he was upon."