Must one fast three days as expiation for an oath sworn in anger, without intending to swear an oath?

If the oath was unintentional, it is considered a laghw yamin (idle oath) for which there is no expiation. However, if the oath was intentional, and it was sworn regarding something contrary to reality, it is a yamin ghamus (perjurious oath). This is one of the major sins that immerses its doer in sin or in Hellfire, and according to the most authoritative opinion, there is no expiation for it; rather, repentance and seeking forgiveness are obligatory. If you wish to offer expiation as a precautionary measure, it is feeding ten poor persons, or clothing them, or emancipating a slave. If you cannot find any of these, then fasting for three days.