Abu Malik (may Allah have mercy on him) said: Oaths are of three types: one upon which expiation is obligatory, another upon which there is no expiation, and a third upon which there is no accountability. The first is that a person swears not to do something and then does it, so expiation must be given. The second is that he deliberately swears a false oath; upon this there is no expiation, rather it is a major sin. The third is that he swears an oath about something thinking it to be true, but in reality it is not so; for such an oath there is neither accountability nor expiation, and this is the idle (laghw) oath.
Hadith Referenceسنن سعید بن منصور / كتاب التفسير / 784
Hadith Gradingمحدثین:سنده صحيح، وتقدم مختصرًا برقم [٧٧٨]، وسنده صحيح أيضًا.