What is the ruling on someone who swore to abandon a sin, then committed it, then expiated for it by fasting but did not complete the fast of expiation, then fell into the same sin again? Is he obligated to repeat the expiation? And is swearing to abandon sins an ill-placed piety that resembles the Children of Israel?

Abandoning sin is a religious obligation. If a servant swears an oath to abandon it, he adds to thew religious obligation the obligation to fulfill his oath, so it is not permissible for him to break it. If he breaks it, his oath is dissolved, and no other expiation is binding on him unless he swears a second oath or intends repetition.

Expiation by fasting is not valid except when incapable of feeding, clothing, or emancipating. It is permissible for the fasting of expiation not to be continuous, though continuity is preferable to avoid scholarly disagreement.

Swearing an oath to abandon sins is not a form of piety, because abandoning sins is obligatory by the very essence of religious law. A Muslim must keep his oath.