What is the ruling on someone who says "By divorce, I will not divorce," and then divorces his wife; and how many divorces are counted against him in this case?

If a man says, "By divorce, I will not divorce," and then divorces his wife, two divorces are incumbent upon him if the wife was consummated: the first by the immediate declaration of divorce, and the second for breaking his oath. As for an unconsummated wife, she is divorced once by the immediate declaration and becomes irrevocably separated. The preponderant view is that one divorce becomes incumbent upon breaking the oath if he said, "By divorce." The husband may take his wife back if he had not divorced her previously. The occurrence of divorce due to breaking an oath is the view of the majority of scholars, while Ibn Taymiyyah holds that only one divorce is incumbent.