Does the oath sworn by the husband to divorce become void if he divorces his first wife, then takes back his second wife, and after that takes back the first one again?

The answer depends on knowing the husband's intention and purpose when he said, "If he marries another, she is divorced," because intentions and purposes are considered in the chapter of oaths. If the husband swore to his wife that he would not marry another, then divorced her with a revocable divorce and remarried, he would break his oath, as Imam Al-Shafi'i mentioned in "Kitab al-Umm."