What is the ruling on a husband forcing his wife to have anal intercourse?

Intercourse with one's wife in the anus is a grave sin, for the Prophet, peace and blessings be upon him, forbade it and cursed its perpetrator. The wife must not obey her husband in this act, and she should threaten him with reporting him to the religious authorities if he forces her to do it again, and warn him of the dire consequences of this act which incurs Allah's wrath.