In summary, there is nothing at all, in what Allāh sent His Messenger (صلى الله عليه وسلم) with, what is a means to evil. Rather, all evil that afflicts a servant, or afflicts him in his worldly affairs or the hereafter, then its cause is sins and disobedience.

... And whatever He wills to occur will occur and whatever He does not will to occur, will not occur. And He, the Sublime, is the Creator of the causes and their effects, there is no Creator besides Him and no Determiner besides Him.

The servant is ordered to take caution against the apparent causes of evil and to avoid them to the extent that is related in the Sharīʿah, such as taking caution from the leper and the sick person and from going to a place of the plague.

But as for what is hidden [obscure], then taking caution against it and avoiding it is not legislated. Rather, it is from the prohibited omen, and indeed, it is having an evil opinion of Allāh the Exalted, without any verified cause. Hence, it is not permissible.

That which is obligatory upon he who wishes good for himself is not to turn towards anything from these false imaginations and deceptive delusions and [instead], to be preoccupied away from them with what repels calamity, such as supplication, remembrance, charity, reliance upon Allāh and belief in His ordainment and decree. And [to know] that whatever He wills to occur will occur and whatever He does not will to occur, will not occur and to say what is related, and from it is: “O Allāh, none comes with the affairs of good but you and none repels the affairs of evil but you, there is no power, nor might, save by You.”^[2]

So when he says that, nothing will harm him.

As for when he surrenders [himself] to these affairs, and opens the door of whispers to his soul in these affairs, or [opens the door to his] worries to Shayṭān and throws of such things into his soul what corrupts his religion and makes his life difficult [with hardship, misery], and perhaps that which he took caution against might befall him as a punishment [for holding evil opinion and harbouring omens].