What is the expiation (kaffarah) obligatory upon one who swore not to masturbate or watch pornography, and then broke his oath multiple times? Does the expiation multiply with the multiplicity of breaking the oath or intentions? And is a new expiation obligatory if he returns to what he swore against after paying the expiation?

The aforementioned oath, "I swore I would never do it," taken with the intention of abandoning masturbation and watching pornography, requires a single expiation. The oath is dissolved as soon as one breaks it regarding either of the two matters, and no further expiation is required thereafter. If multiple oaths are taken concerning a single obligation—even if related to multiple actions—and one breaks all of them before performing expiation, then only one expiation is due, because similar expiations merge.