This Hadith means that nothing is ominous by itself. It is, however, true that because of their certain characteristics, certain things become ominous (troublesome) for certain persons. For example, if one has a small house or bad neighbours, he does not feel happy and peaceful in it. If one's wife is sterile or rude or abusive or immoral, etc., such a woman is ominous for him, that is, she is a source of trouble and tension rather than that of happiness for him. If one has a horse which is not used for Jihad, or is so ill-natured that it neither goes well ordinarily or with whipping, nor does it behave when left to its own will, then it has an ominousness in the sense that it does not serve the purpose of the master.