Shevuot 30A

מתני׳ שבועת העדות נוהגת באנשים ולא בנשים, ברחוקין ולא בקרובין, בכשרין ולא בפסולין; ואינה נוהגת אלא בראוין להעיד.

Mishnah: The oath of testimony is practiced with regard to men but not with regard to women, with regard to non-relatives of the litigants but not with regard to relatives, with regard to those fit to testify but not with regard to those unfit to testify due to a transgression that they performed. And the oath of testimony is practiced only with regard to those fit to testify.

בפני בית דין ושלא בפני בית דין ⁠– מפי עצמו, ומפי אחרים אין חייבין עד שיכפרו בהן בבית דין. דברי רבי מאיר. וחכמים אומרים: בין מפי עצמו ובין מפי אחרים ⁠– אינן חייבין עד שיכפרו בהן בבית דין.

The oath of testimony is practiced both in the presence of a court and not in the presence of a court, when the potential witness takes the oath on his own. But if the oath is administered by others and those denying that they witnessed the incident in question neither take an oath nor answer amen to the administered oath, they are not liable until they deny any knowledge of the incident in question in court. This is the statement of R' Meir. And the Rabbis say: Whether one of the witnesses takes the oath on his own or whether the oath is administered by others, the witnesses are not liable until they deny any knowledge of the incident in question before the litigants in court.

וחייבין על זדון השבועה, ועל שגגתה עם זדון העדות, ואינן חייבין על שגגתה. ומה הן חייבין על זדון השבועה? קרבן עולה ויורד.

And one is liable for the act of taking a false oath with intent and for an unwitting act of taking a false oath, i.e., he is unaware of the liability for taking a false oath, provided that he takes the oath with intent in terms of the testimony, i.e., he takes an oath that he has no knowledge of the matter even though he knows that he witnessed the incident. But witnesses are not liable for taking the oath if they were unwitting in terms of the testimony, i.e., they believe that they have no knowledge of the matter. And what are they liable for by taking a false oath with intent? They are liable to bring a sliding-scale offering.