Some Rulings on Oaths

Question: What is the ruling on a person who swears an oath denying that something happened, when in fact it did happen but he does not know it occurred? By way of illustration: we once did something that harmed another person. That person came and asked our father whether we had done it. Our father denied it and swore an oath that we were innocent, even though we actually had done it, but our father was unaware of that. May we offer the expiation on his behalf without his knowledge, or must we inform him so that he can expiate for himself, or is there no sin involved at all?

Answer: First of all, a Muslim must guard his tongue when it comes to oaths and should not rush into swearing except when there is a genuine need and he is certain about what he is swearing to. If a person swears that something did or did not take place on the basis of what he predominantly believes to be true, and later learns that reality was otherwise, he is not sinful; he swore according to his best judgment. Such an oath is classed as laghw al-yamin—an unintentional or idle oath.

If, however, he knowingly and deliberately swears falsely, he is sinful. No expiation (kaffarah) is prescribed for a deliberate false oath; rather, he must seek Allah’s forgiveness and repent to Him, and Allah accepts the repentance of those who repent.

Expiation becomes obligatory only for an oath intentionally taken regarding a possible future matter—whether to do something or to refrain from it—and then the person breaks that oath. Expiation applies exclusively to oaths about future actions. As for an oath concerning a past event: if the person lies deliberately, he is sinful and must repent to Allah; but if he swore on what he thought most likely and later discovered he was mistaken, there is no blame on him, for that is considered an unintentional oath.