Is one obligated to fast due to breaking an oath not to commit sins, and what is the number of days one must fast? Is expiation required for each instance of breaking the oath, or only once?

If the oath is taken by one of the names of Allah, or one of His attributes, or by the Holy Quran, and its repetition is for the purpose of emphasizing abstaining from a sin, then it entails a single expiation (kaffarah), which is fasting for three days if one is unable to feed or clothe. If he breaks his oath once, the oath is dissolved, and he is not required to repeat the expiation by repeatedly falling into what he swore against, unless he renews the oath. What appears evident is that he owes one expiation for the repeated oaths, and this expiation does not multiply with the repetition of the sin after breaking the oath; rather, it is the sin itself that increases.