Shevuot 26a:14שבועות כ״ו א:י״ד
§ The Sages taught in a baraita: The verse states: “Or if anyone take an oath clearly with his lips to do evil, or to do good, whatsoever it be that a man shall utter clearly with an oath, and it is hidden from him; and, when he knows of it, be guilty in one of these things” (Leviticus 5:4). The phrase “a man…with an oath” serves to exclude a victim of circumstances beyond his control from liability to bring an offering. The term “and it is hidden” serves to exclude from liability one who broke his oath intentionally, as he does not deserve to be able to achieve atonement through bringing an offering.
תָּנוּ רַבָּנַן: ״הָאָדָם בִּשְׁבוּעָה״ – פְּרָט לְאָנוּס. ״וְנֶעְלַם״ – פְּרָט לְמֵזִיד.