Keritot, Chapter Two, Mishnah Two
Usually a person brings a sacrifice only when s/he transgresses unwittingly. For instance, if one willfully breaks Shabbat, one does not bring a sacrifice. But if one didnt know that a certain act is forbidden on Shabbat and then he performed that act, he can bring a sacrifice to atone for the transgression. However, there are four cases in which a person must bring a sacrifice even if he intentionally transgresses.
The following bring a sacrifice for willful as well as for inadvertent transgressions:
1) One who has intercourse with a female slave,
2) A nazirite who has become unclean,
3) For a false oath concerning testimony;
4) And for a false oath concerning a deposit.
Section one: This shall be explained in mishnayot 4-5 of this chapter.
Section two: A nazirite is not supposed to defile himself through contact with a dead body (see Numbers 6:9-12). If he does he must bring two sacrificesa hatat and an olah. He is liable for these sacrifices even if he intentionally comes into contact with the dead.
Section three: If a person swears that he does not know any testimony for another person, and it turns out that he did know testimony, he must bring a sacrifice to atone for his sin. By its very nature, this false oath had to have been done intentionally, and therefore we have another case of a person who brings a sacrifice for an intentional sin. This topic was discussed in Shevuot 4:2-5.
Section four: If a person swears falsely that someone elses property was not deposited with him, and then it turns out that he was lying, he brings a sacrifice. Again, by its very nature this is an intentional sin. This topic was discussed in Shevuot 5:1-2.