'(There is) no 'Adwa (no contagious disease is conveyed without Allah's permission)
Abu Huraira, may Allah be pleased with him, narrated:"Allah's Messenger, may the peace and blessings of Allah be upon him, said, '(There is) no 'Adwa (no contagious disease is conveyed without Allah's permission). nor is there any bad omen (from birds), nor is there any Hamah, nor is there any bad omen in the month of Safar, and one should run away from the leper as one runs away from a lion.''
The Prophet (peace and blessings of Allah be upon him) was sent as a teacher to complete the good morals, he supported the sound beliefs and nullified the false ones.
The messenger of Allah, may the peace and blessings be upon him, used to spare no effort to eliminate the myths inherited by the Arabs and the non Arabs. They transferred such false beliefs through the generations until they considered it firmly established facts.
Believing in the Teyara (bad omens), Hamah and Safar.
Believing in the Teyara (bad omens) is a sort of pessimism, taken from letting the birds then to do or to refrain from doing something according to their direction of flying.
The Hamah is what comes out in the place where the victim was killed according to the belief of the ignorant Arabs.
As for Safar: the scholars differed in interpreting this word some of them held the opinion that was is meant is to fear the bad omens of the month of Safar. However, some of them said: what is meant is a snake in the abdomen, when one feels hungry it says feed me.