What is incumbent upon me after establishing marital relations during menstruation due to the husband's ignorance and the wife's knowledge?

There is no sin upon the husband nor expiation if he had intercourse with his wife while ignorant of her menstruation, due to the حديث (Prophet's saying): "Allah has forgiven my Ummah for their mistakes, forgetfulness, and what they are coerced into." As for the wife, she erred by not informing her husband, and she must repent with remorse, but there is no expiation upon her; for expiation, if due, would be on the husband, and it may not be due on the husband because of his ignorance.