What is the ruling of Islamic law regarding a wife who demanded that her husband, after he admitted to her that he went to a strange woman, swear by Allah falsely upon the Qur'an that he did not do so, and that she would be unlawful to him and divorced if he had done it or would repeat it? And what are the consequences for the husband who swore falsely to get out of the problem? And what is the sin of whoever advised him to lie to preserve their home?

The man should have concealed himself, and his lie is permissible if it is the only way to conceal. If concealment is not possible except by swearing a false oath, then its permissibility is not far-fetched. As for him conditioning his wife's divorce and her prohibition on his committing the reprehensible act, there is a difference of opinion on this. The majority validate it, while some scholars, like Ibn Taymiyyah, do not validate it. He is of the view that whoever swears by divorce falsely, knowing he is lying, his wife is not divorced, and he is not obligated to offer expiation for an oath. If you advised the man to lie for concealment without knowledge of the Shariah ruling, then you must repent and be cautious about speaking on matters of Shariah without knowledge.