Thus, good deeds either stand in opposition to bad deeds or prevent them: they are either their opposite or a barrier against them. Bad deeds occur only when the good deeds that prevent them are weak, as the Prophet, may Allah bless him and grant him peace, said:

“No adulterer is a believer while committing adultery; no thief is a believer while stealing; and no one who drinks wine is a believer while drinking it.”

Faith in its fullness and true reality prevents such acts. They therefore occur only when there is some weakness in faith that deprives it of its completeness.

As for leaving bad deeds, this may mean merely their absence. Pure absence neither excludes anything nor entails anything. Indeed, a person whose heart is unoccupied is more susceptible to bad deeds than to good ones. Alternatively, it may mean deliberately refraining from committing them. Such restraint requires believing that they are evil and intending to abandon them. This belief and moderation are two commanded good deeds, and they are among the greatest good deeds.

It is thus established that the presence of good deeds prevents bad deeds, whereas the absence of bad deeds does not necessarily bring about good deeds. The presence of good deeds therefore combines both benefits, unlike the mere absence of bad deeds, which involves only one. This is the point being made.