Is an expiatory offering (kaffarah) for breaking an oath obligatory for someone who broke their oath forgetfully, then continued to do what they swore to abandon?

If one swears to abstain from something, then does it out of forgetfulness or error, he does not break his oath and is not required to offer expiation, according to the majority of scholars. However, to be on the safer side and absolve oneself, it is more prudent to adopt the view that expiation is required. If the action was intentional, then expiation is obligatory, and it does not multiply with the repetition of the act unless the wording of the oath or the expiation is repeated with each instance of breaking the oath.