What is the ruling on a husband frequently swearing an oath of divorce upon his wife if she does something without his knowledge, or spies on him, or sleeps at her family's house, and does this oath take effect?

If a husband frequently swears by divorce, he has done wrong by violating the prohibition of swearing by other than Allah, and by mistreating his wife. If a husband swears by divorce and intends for it to occur upon the fulfillment of the condition, his divorce takes effect. Similarly, divorce takes effect even if he only intended a threat, according to the majority of jurists. Some scholars hold that if he did not intend divorce, only an expiation for breaking an oath is required of him, but it is preferable to refer the matter to a Sharia (definition) court. The wife must obey her husband in what is good and strive to earn his satisfaction.