What should one do if he has conditioned his wife's divorce upon her greeting another woman, and he now regrets his oath and wishes to retract it?

The majority of scholars hold that a conditional divorce takes effect upon the fulfillment of the condition, regardless of whether divorce was intended or merely emphasis, or anything else, and that the husband cannot retract his oath. This is the fatwa we adhere to.

However, Shaykh al-Islam Ibn Taymiyyah is of the view that if the one swearing the oath did not intend to make the divorce conditional but rather intended prevention or encouragement, then divorce does not occur upon breaking the oath, and he must offer an expiation for an oath. But if he intended to make the divorce conditional, then he can retract it, and nothing takes effect.

Based on this, if the wife greets that woman, divorce will take effect according to the majority of scholars. Whereas, according to Ibn Taymiyyah, if you intended to make the divorce conditional, you may retract it, and if you intended emphasis, then you must offer an expiation for an oath.

Given the difference of opinion on this matter, it is preferable to refer it to a Sharia court or a reliable scholar.