The ruling on the expiation for an oath regarding a past matter

Question:
Honorable Shaykh, the questioner says: I swore an oath believing that something was true, so do I have to break it?

Answer:
The expiation is only obligatory for a binding oath, as stated in the verse: to the end of the verse. As for an oath regarding a past matter, swearing that it is true or that it is not true, there is no expiation for that. However, if he is lying intentionally, he commits a sin, and he must seek forgiveness and repent. This is the grave oath (al-yamin al-ghamur); for it, one must seek forgiveness and repent, but there is no expiation. For example, if he says, “By Allah, so-and-so is coming,” when he is not coming and he knows he is not coming, and he intentionally lies, he commits a sin. He must repent and seek forgiveness and not return to such behavior, but he does not owe an expiation. The expiation is for future matters, such as saying, “By Allah, I will do such-and-such,” or “By Allah, I will not do such-and-such.” This concerns future matters, not past ones. Yes.