Is expiation permissible for all types of vows?

Vows are of different types. Some must be fulfilled by consensus, and expiation (kaffara) is not sufficient for them. This is the vow of obedience (nadhr al-taa'a), and it has three forms: 1. Committing to an act of obedience in return for a blessing or warding off an adversity, such as saying, "If Allah cures me, then I owe it to Allah to fast for a month." This must be fulfilled by the consensus of scholars. 2. Committing to an act of obedience without a condition, such as saying, "I owe it to Allah to fast for a month." This must be fulfilled according to most scholars. 3. Vowing an act of obedience that is not originally obligatory, such as i'tikaf (seclusion in a mosque) or visiting the sick. This must be fulfilled according to the general body of scholars.

There is no room for expiation in a vow of obedience unless the one who made the vow is unable to fulfill it. If one is unable to fulfill it, then he must offer an expiation for an oath (kaffarat yamin). If the inability is temporary, one should wait for it to cease. If the inability persists and its cessation is no longer hoped for, then one moves to expiation and fidya (redemptive feeding). The basis for fulfilling a vow of obedience is the saying of the Prophet, peace and blessings be upon him: "Whoever vows to obey Allah, let him obey Him."