and this is also one of the narrations transmitted from Aḥmad (1).

3. He is given the choice either to carry out what he bound himself to do or to pay the expiation for an oath.
   This is the well-known position in both the Ḥanbalī and Shāfiʿī schools (2).

   If we hold that expiation is required, yet he nevertheless fulfils his vow, does that cancel the expiation? The Shāfiʿī jurists have two opinions on the matter. Abū al-Maʿālī and others criticised the view that the expiation is dropped, but their criticism is misplaced; that opinion is unquestionably correct. Expiation is due only upon breach, and when he has fulfilled his vow no breach has occurred, leaving no ground for expiation.

   Should it be said, “The very effect of this contract is to oblige expiation,” we reply: Yes, in essence it is an oath, and an oath only entails expiation when it is broken; there is no breach when it is honoured. This is made clear by the fact that if he had sworn the same oath by Allah and then kept it, no expiation would be required. Likewise, if he said, “By Allah, should I do such-and-such I shall give charity,” and then he did the act and gave the charity, no expiation would be incumbent upon him (3).

Section
If the two parties specify a particular type of bow, that type becomes binding, and it is not permissible to switch to another type except with their mutual agreement.