Asalam o Alaikum!!!! I am so sorry that I am asking so many questions but these thoughts are really disturbing me or maybe I am suffering from satanic whispersSo the question is that if someone accuses someone of Zina or immortality infront of us should we advise them to repent sincerely and ask for forgiveness (if the matter reached the accused) or should we report them to Islamic authorities especially if the accuser is unaware that it is a huge sin and wants to repent for what she did? Please reply and as soon as possibleJazak Allah

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

The act of this woman should be denied. That is because enjoining what is lawful and prohibiting what is unlawful is a collective duty that turns into an individual duty in case there is just one person to observe it. In his commentary on Saheeh of Imam Muslim, Imam An-Nawawi said, "Enjoining what is lawful and prohibiting what is unlawful is a collective duty, meaning that if it is fulfilled by some, the others would not be blamed for not doing it. However, if it is not fulfilled without a valid legal excuse or fear, all the members of the community, who could do it, would be sinful. Furthermore, this collective duty may be turned into an individual duty as in the case when there is the only person who knows how to duly fulfill it (i.e., the lawful) or remove it (i.e., the unlawful)." Denial of the unlawful should be observed thoughtfully and in a gentle way. It should also be based on showing the danger of her speech by which she committed two sins, that is, backbiting and slandering – two acts totally prohibited by the Quran. Allah, The Exalted, says (what means): {Indeed, those who [falsely] accuse chaste, unaware and believing women are cursed in this world and the Hereafter; and they will have a great punishment} [Quran, 24:23] and {And those who accuse chaste women and then do not produce four witnesses - lash them with eighty lashes and do not accept from them testimony ever after. And those are the defiantly disobedient.} [Quran, 4:23] So, she must repent to Allah, the Exalted. As for the conditions of repentance, you can consult Fatwa 86527.

However, she should ask the wronged woman to forgive her, especially since she knew about backbiting and slandering.

Furthermore, in case this woman is unaware of the danger of her acts as you mentioned and that she wants to repent to Allah, you should conceal her fault and not report it to the ruler. On that, Imam An-Nawawi said, “As for the recommended conceal (of faults), it is for those people who are not known for hurting others or spreading corruption. Yet, as for those who are well-known for these matters, it is not recommended to conceal their faults; rather, they should be reported to the ruler in case no corruption would take place. That is because concealing the faults of these people makes them more eager to do corruption and to violate the rights, which also encourages others to do the same.”

Allah knows the best.