How many expiations are required for someone who swore to himself that he would not practice masturbation for a certain period, then did so before the period ended, and repeated that in the same manner?

If someone swears not to do something and then does it, they have broken their oath (hanith) and atonement (kaffarah) becomes obligatory upon them. If they perform the atonement, and then swear again and do the same thing, another atonement is due upon them, by scholarly consensus. However, if they break their oath but do not perform atonement, and then swear again and break that oath as well, then according to the majority of scholars, two atonements are due, whereas the Hanbalis hold that only one atonement is due. And if someone swears not to do something and does not break their oath, then swears a second time and then breaks that oath, the preponderant opinion is that only one atonement is due. This is the view of the majority, in contrast to the Hanafis, who say that an atonement is due for each oath, and some Malikis and Shafi'is, who differentiate between intending emphasis and intending a new, separate oath.