What is the difference between a false oath and an unfulfilled oath, and is expiation permissible for a false oath?

Oaths are divided into three types:

1. A thoughtless oath (Yamin al-Laghw): This is an oath not intended as a vow, or swearing about something one believes to be true, but it turns out to be otherwise. There is no expiation for it according to most scholars.

2. A binding oath (Yamin Mun'aqidah): This is when one swears to do or not to do something, and then breaks the oath. Expiation is required for it, which is feeding ten needy people, or clothing them, or freeing a slave. If one cannot find any of these, then fasting for three days.

3. A perjurious oath (Yamin Ghamus): This is swearing falsely while knowing it. There is no expiation for this according to the majority of scholars; rather, repentance atones for it.