2,760. Permitting Part of a Vow
Hilchos Nedarim 4:11
Let’s say that someone makes an oath or a vow not to benefit from a group of people. If he has his vow or oath permitted regarding one of them, all the rest are also permitted. This is because when a vow is partially permitted, all of it becomes permitted. If someone says, “I will not benefit from person A, and from person B, and from person C,” then if he has the first person permitted, all of them become permitted. If has the last person permitted, then only that person is permitted, but not the others. If he says, “I will not benefit from him, nor from him, nor from him,” then he must seek to have each one permitted individually. (Since he didn't link them by saying “and,” each one is considered an independent vow.) The same is true in all comparable cases.
Hilchos Nedarim 4:12
If someone took a nazirite vow, a vow to bring an offering, an oath or a vow (of prohibition), but doesn’t know which one he took, one inquiry can have all of them permitted.