Is the money taken by the husband lawful for him, in the event that he saw a man with his wife in seclusion on his bed, and they reconciled for a sum of money?

It is forbidden for a man to take money in exchange for concealing such an act, as this indicates a lack of 'dayyooth' (cuckoldry) and a lack of protective jealousy over one's honor. The woman must repent of her evil deed. If she does not, there is no good for her husband in keeping her. There is a serious warning against the danger of a woman allowing a foreign man to enter upon her and be in seclusion with her. The man must be firm with his wife, obligate her to cover and wear the hijab, and prevent her from causes of temptation, in accordance with his 'qawamah' (guardianship) over her, which means taking care of worldly and religious interests, obligating them to fulfill the rights of Allah, and restraining them from corruption.