Islam always calls Muslims to have a strong faith. Thus, anything which would shaken this belief must be rejected. An example of that is the belief that some animals would bring harm. If any body believes in such superstitions, then his/her faith must be checked. A good believer should make sure that everything whether good or bad is coming from Allah. Black cats are just normal cats and they have nothing to do with Jinn. Jinn is another creation like human beings, so they have the good and the bad.

It must be known that these myths – and many others – come under the heading of superstitions that are groundless. There is no limit to such myths among the people. Some regard seeing certain things as a bad omen – such as seeing an owl or a black cat; some regard hearing certain things as a bad omen – such as hearing the sound of an owl or a crow. They even regard verses in the Book of Allah as omens, if it is seen in the Mushaf or heard from one who is reading! – such as a verse which speaks of warning or punishment. Some of them regard numbers as unlucky, such as 13; or they regard certain times as unlucky times, such as Wednesdays, or the month of Shawwal for those who want to get married. Some regard certain places as unlucky, such as a place in which a crime occurred, or they regard certain types of people as a bad omen, such as the lame or the blind, or the poor or needy.

It was narrated from AnasibnMaalik (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: “There is no adwa (transmission of infectious disease without the permission of Allah) and no tiyarah (superstitious belief in bird omens), but I like optimism.” They said, “What is optimism?” He said, “A good word.”  Narrated  by al-Bukhari and Muslim.

It was narrated that ‘Abd-Allah ibnMas’ood said: The Messenger of Allah (peace and blessings be upon him) said: Tiyarah (superstitious belief in omens) is shirk.”Narrated by al-Tirmidhi, Abu Dawood, and IbnMajaah.

The Arabs used to regard certain birds, times and persons as unlucky, and this is shirk as the Prophet (peace and blessings be upon him) said.

What matters is that no one should pay any attention to a superstition, because it will spoil his life. What we should do is to follow the example of the Prophet (peace and blessings be upon him) who liked optimism, as was narrated by al-Bukhari and Muslim. We should be optimistic, not pessimistic, like some people who try something time after time, then they become pessimistic and think that they will never succeed in it, so they give it up. This is wrong, because if you think that something is good,
you should not give it up at the first attempt; try again and again until Allah makes it easy for you.