What is the expiation for someone who swore four times to abandon a sin, then committed it, and is expiation required of him if he commits the sin without swearing after the fourth time?

If you swore several oaths and broke each one before swearing the next, then you owe an expiation for each oath you broke. However, if all oaths were broken before expiating for them, then only one expiation is due. The expiation for an oath is feeding ten needy persons, or clothing them, or freeing a slave. If you cannot find any of these, then fasting for three days. If you committed a sin without having sworn an oath, then no expiation is due, but rather sincere repentance. One must be wary of sin and frequent swearing, resolve firmly to abandon sin, and seek assistance from Allah Almighty.