It is narrated from Sayyiduna al-Sa'ib bin Yazid (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "There is no disease that is contagious by itself, there is no ill omen in Safar, and there is no reality to the hamah."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6629