Musnad Ahmad 26:140

Waki’ narrated to us, Sufyan narrated to us, from Salamah ibn Kuhayl, from ‘Isa ibn ‘Asim, from Zirr ibn Hubaysh, from ‘Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Taking omens is shirk (polytheism)." And there is not one of us except [that he experiences something of it], but Allah removes it through reliance upon Him (tawakkul).