What is Islam's ruling regarding a husband abandoning his wife for seven days after an argument and going to his other wife on her night, while swearing that his wife said words she did not utter? And what should the wife do about this misunderstanding, and what is the ruling concerning the day she missed?

A husband must be just between his wives. He is not permitted to abandon his wife without a valid legal reason. If there is disobedience (nushuz) from the wife, then abandonment in bed is permissible, and forsaking speech should not exceed three days. It is not lawful for a husband to abandon his wife by leaving the house and spending the night with another wife. Rather, he must spend the night with her, and he must make up the nights he unjustly missed with his wife.