Must a person fast the days he swore to fast as a punishment for himself each time he breaks his oath, or is there another expiation he can perform?

If a person swears not to do something and then does it, he must fast for three days. If he does not fast, he must offer expiation for the oath. The fasting or expiation is not repeated if the act is repeated, unless the wording of the oath or his intention implies repetition, or custom indicates it. Among the words that imply repetition are: "every time" and "whenever." If what he mentioned was a vow, meaning he vowed to fast for three days if he did something, then he must fulfill the vow whenever the condition is met. It is not repeated by repeated transgression unless he intended repetition or the wording of the vow indicates it. As for fasting in Rajab, nothing authentic has been reported regarding its specific فضائل (virtues).