Does divorce occur if the wife is beaten again after swearing on the Qur’an not to do so, knowing that the husband was forgetful when he beat her? And does this condition become void after one pronouncement of divorce is counted and the wife is returned to his wedlock?

Summary:

If a husband swears an oath not to hit his wife, and makes her divorce contingent upon it, then hits her forgetfully, he is considered to have broken his oath (to have "hanith") according to the Hanbalis and some Malikis (the well-known opinion among them). However, he is not considered to have broken his oath according to the Shafi'is and some Malikis. If he breaks his oath, divorce occurs according to the majority of scholars, and he is obligated to pay the expiation for an oath (kaffarat yamin). He may take his wife back if it was the first or second divorce and before her waiting period (iddah) ends. If he takes her back, his oath is dissolved, and hitting her thereafter will not result in divorce if the wording of the oath does not imply repetition. It is permissible to hit one's wife within legitimate Islamic guidelines.