Does committing a sin intentionally diminish faith, remove light from the face, and expel the doer from the ranks of the righteous, even with immediate repentance? And does committing a sin inadvertently affect a person's knowledge, as happened to Imam Al-Shafi'i and the person who entered upon Uthman?

Sins cause a decrease in faith and a darkening of the face. If the perpetrator repents with sincere repentance, these effects are removed. Among the effects of sins are deprivation of beneficial knowledge and sustenance, and a sense of alienation in the heart and between people. As for committing a sin out of forgetfulness or ignorance by someone excused by ignorance, there is no sin in it, and the mentioned effects do not apply to it.