It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "There is no contagion that spreads by itself, there is no reality to evil omens, there is no reality to the owl omen, and there is no reality to the ill-luck of the month of Safar." A man said: O Messenger of Allah! We take a mangy goat and put it among the goats, and they all become mangy. He (peace and blessings be upon him) said: "Then who made the first one mangy?"
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11714