for doing what he vowed, thus it does not necessitate an expiation, just like a vow of the impossible. As for us, we rely on what was previously stated in the section before it. Regarding the hadith of the woman who vowed to walk, the expiation was commanded in another hadith; Uqbah ibn Amir narrated that his sister vowed to walk to the Sacred House of God, and the Messenger of God (peace and blessings of God be upon him) was asked about that, so he said: "Command her to ride, and to offer an expiation for her oath." This is authentic (sahih) and was recorded by Abu Dawud. This is an addition that must be accepted, and it is possible that the narrator of the hadith narrated part of it and omitted another, or that the Prophet (peace and blessings of God be upon him) omitted mentioning the expiation in part of the hadith, referring to what was known from his hadith in another place. Included in this category is the case if one vows to perform a disliked act, such as divorcing his wife; this is disliked, based on the saying of the Prophet (peace and blessings of God be upon him): "The most hateful of permissible things to God is divorce" (41). Therefore, it is recommended that he not fulfill it and offer an expiation. If he does fulfill his vow, there is no expiation upon him, and the disagreement regarding it is like the one before it. The sixth category: The vow of that which is obligatory, such as the prescribed prayer. Our scholars said: It is not a binding vow. This is also the position of the companions of al-Shafi'i, because a vow is a commitment, and it is not valid to commit to something that is already incumbent upon one. It is possible that the vow is binding in a way that necessitates an expiation of an oath if he abandons it, just as if he had sworn to perform it; for a vow is like an oath, and the Prophet (peace and blessings of God be upon him) named it an oath (42). Likewise, if he vows a sinful act or a permissible one, it is not binding upon him, and he must offer an expiation if he does not perform it. The seventh category: The vow of the impossible, such as fasting yesterday. This does not become binding and does not necessitate anything, because its binding nature cannot be conceived, nor its fulfillment. If he swore to perform it, an expiation would not be required of him, so a vow is even more so. The principle of this chapter in the correct position of the school is that a vow is like an oath, and its requirements are the same as its requirements, except in the necessity of fulfilling it,