Musnad Ahmad 28:567

Hassan narrated to us, Ibn Lahi'ah narrated to us, Ibn Hubayrah informed us, from Abu Abd al-Rahman al-Hubuli, from Abdullah ibn Amr, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever is turned back from a need by omens (al-tiyarah), he has committed shirk." They said: "O Messenger of Allah, what is the expiation for that?" He said: "That one of them says: 'O Allah, there is no good except Your good, and no omen except Your omen, and there is no god other than You.'"