Whose responsibility is the expiation if a person falsely swears "By God"?

If a person swears falsely by Allah, they must repent and seek forgiveness, because this is one of the major sins (al-Yamin al-Ghamus - the dive-in oath, i.e., an oath that immerses the swearer in sin). Its expiation, according to the majority of scholars, is repentance and seeking forgiveness. Some scholars, however, are of the opinion that expiation is obligatory in addition to repentance. As for the questioner being the one who swore the oath, there is nothing upon them; the sin is upon the liar.