What is incumbent upon one who swore not to open his phone before a certain time, then opened it?

The general principle is that whoever swears an oath not to do something and then does it, must offer expiation for breaking an oath. However, if the reason that prompted the oath no longer exists, such as someone who swore not to open their mobile phone for studying, but then opened it during a trip that has no relation to studying, then there is no breaking of the oath. An oath is constituted based on the intention of the one swearing or the reason that prompted the oath. The majority of jurists (Hanafis, Malikis, and Hanbalis) have agreed on considering the reason that prompted the oath in fulfilling or breaking it.