In this manner...
In this manner, actions manifest the motives that are fixed in the minds of the doers. Conversely, these traits may remain hidden if one does not do any action that could prove their existence in one’s mind. We have said above that “what is in your souls” means what is settled in your minds. It does not mean ineradicable and firmly rooted characteristics; rather it refers to the substantial existence of such characteristics from which actions may emanate.
The two alternatives, “whether you manifest..." and “hide it", show that those characteristics are capable of being shown or hidden; it may be a well-ingrained trait or some appropriate psychological state. But it does not, and cannot, mean passing notions and transient ideas that invade one’s mind without one’s intention; for example, the mental image of a sin when one has no intention or inclination to do it.
The words of the verse do not include such involuntary notions, because they are not “settled” in the mind, nor does any action emanate from them. The verse, in short, says that mental states, the characteristics and traits settled in mind, are the basis of a man’s actions, obedient as well as disobedient; and Allah will call man to account for them.
In this respect, this verse has the same significance as the following verses: Allah will not call you to account for what is vain in your oaths, but He will call you to account for what your hearts have earned (2:225). . . . his heart is surely sinful (2:283). . . . surely the hearing and the sight and the heart, all of these, shall be questioned about that (17:36).
These verses prove that there are some conditions and characteristics of hearts, that is, minds, for which man will be called to account. The following verse also proves it Surely (as for) those who love that scandal should circulate respecting those who believe, they shall have a grievous chastisement in this world and the hereafter. . . (24:19). It shows that the chastisement shall be because of the “love” of circulating scandal; and love is a state of mind.
This is the apparent and clear meaning of this verse. It proves that man shall be called to account for what is settled in his mind, whether he hides it or shows it. But the verse is silent on the questions as to whether the chastisement in all cases - manifesting it or hiding it, acting according to one’s intention or not doing so, succeeding in the intended transgression or not succeeding - will be the same or different.