Leviticus 5:4

בשפתים [OR IF A SOUL SWEAR, PRONOUNCING] WITH HIS LIPS [FOR HARM, OR FOR GOOD] — with his lips but not merely in his heart (Sifra, Vayikra Dibbura d'Chovah, Section 9 2; Shevuot 26b). להרע TO DO HARM to himself, או להטיב OR TO DO GOOD to himself, — as for instance, if he swears: “I shall eat” (which is להטיב), or, “I shall not eat” (להרע), “I shall sleep” (להטיב) or, “I shall not sleep” (להרע) (cf. Shevuot 27a). לכל אשר יבטא WHATSOEVER IT BE THAT A MAN PRONOUNCETH [WITH AN OATH] whatsoever it be: — this is intended to include the case where the oath refers to something that happened in the past (e.g., he swore, “I have eaten” etc. but he has not) (Sifra, Vayikra Dibbura d'Chovah, Section 9 8; Shevuot 26a). ‎‏ונעלם ממנו AND IT BE HID FROM HIM (he forgot that he had taken such an oath) and consequently he violated his oath. — All these cases come under the law of “a sacrifice of higher or lesser value” (according to pecuniary conditions), as is set forth here (vv. 6—13): but an oath which involves the false repudiation of a claim to money does not come under the law of this sacrifice but under that of a guilt-offering (v. 25).

א֣וֹ נֶ֡פֶשׁ כִּ֣י תִשָּׁבַע֩ לְבַטֵּ֨א בִשְׂפָתַ֜יִם לְהָרַ֣ע ׀ א֣וֹ לְהֵיטִ֗יב לְ֠כֹ֠ל אֲשֶׁ֨ר יְבַטֵּ֧א הָאָדָ֛ם בִּשְׁבֻעָ֖ה וְנֶעְלַ֣ם מִמֶּ֑נּוּ וְהוּא־יָדַ֥ע וְאָשֵׁ֖ם לְאַחַ֥ת מֵאֵֽלֶּה׃

or if a person swear, pronouncing with his lips to do evil, or to do good, whatever it be that a man shall pronounce with an oath, and it be hid from him; when he knows of it, then he shall be guilty in one of these.