What is the ruling concerning a Muslim who fabricates lies against his Muslim brethren?

Accusing a Muslim of an evil deed without proof is one of the grave sins and necessitates punishment. It is also a forbidden form of backbiting, as Allah likened backbiting to eating the flesh of one's dead brother. And for whoever loves that indecency should be spread among those who believe, there is a painful punishment. Whoever has slandered his brother or accused him must repent and seek forgiveness from his brother, and avoid delving into matters that harm a Muslim. For in the hadith, "Whoever believes in Allah and the Last Day should speak good or remain silent." It is not permissible to accuse a Muslim of immorality (fisq) or disbelief (kufr) unless he truly is so; otherwise, the accusation reverts to its accuser. Accusing a Muslim of drinking alcohol is an accusation of immorality. So, whoever accuses his brother of something that is not in him, Allah will test him with something similar to what He tested his brother with. A Muslim has been forbidden from spying on his brother and seeking out his faults. If he sees something suspicious, he should advise him and not expose him unless he openly commits evil.