If Li`an is done, four rulings are pertaining to it:
1- The drop of the prescribed punishment or the discretionary punishment which the false accusation entails on her or on him. If a husband accuses his wife by naming the man with whom she committed adultery, the prescribed punishment of false accusation is dropped from him because Hilal ibn Umayyah accused his wife of having a relationship with Sharik ibn Sahma' without mentioning him in his Li`an and the Prophet (peace be upon him) did not apply the prescribed punishment on Sharik nor did he disciplined him, and because Li`an is a proof for one of both sides, so it is a proof against the other as the case of testimony which will be in favor of someone and against the other.
2- Separation even without the power of the judge because Li`an entails perpetual prohibition, so it does not depend on the power of the judge such as suckling and separation done by the power of the Prophet (peace be upon him). Li`an is not done except by the separation of the judge because of the saying of Ibn `Abbas in his Hadith: Then the Prophet (peace be upon him) separated between them. It was reported in the Hadith of `Uwaymir that he accused his wife of adultery and they were brought to the Messenger of Allah (peace be upon him). `Uwaymir said: O Messenger of Allah, I have attributed lies against her. Then he divorced her thrice before the Prophet (peace be upon him) commanded him. [Reported by Al Bukhari and Muslim]. This Hadith is a proof that separation is done by submitting the case of Li`an to the judge as was reported in the book of Al Kafi.
3- Perpetual prohibition because of the saying of Sahl ibn Sa`d: The habit of those who submit the case of Li`an is separation between them forever. [Reported by Al Jawzjany].
`Umar (may Allah be pleased with him) said: The spouses who pratice Li`an should be separated forever. [Reported Sa`id, and Ali and Ibn Mas`ud reported a similar narration].
4- Denying the attribution of the child by saying: I bear witness by Allah that she committed adultery and this is not my child. The apparent meaning of the words of Abu Bakr is denying the attribution of the child because of the Hadith of Hilal ibn Umayyah who accused his wife before giving birth and the Prophet (peace be upon him) said: "Wait for her birth, but if she gives birth by such and such..." Then he denied the attribution of the child to him. Ibn `Abdul-Barr said: There are many narrations that confirm the previous Hadith. Li`an was not reported after birth, and the condition of Li`an is that it should not be preceded by the husband’s admission of the child or of his twin or of his acceptance to the congratulations of people or even saying: Amen at invoking Allah for him because of the child or by the delay of denial without an excuse because Li`an is meant to ward off an evil which should be done instantly such as the choice of pre-emption.