Kerisos 6:2-3

Krisos 6:2

A definite guilt offering is different from a conditional guilt offering. If a person discovered that he didn’t sin before a definite guilt offering is slaughtered, the animal is sent out to graze with the flock; if after slaughter, the animal must be buried. If the blood was already sprinkled, the flesh must be taken out to be burned. An ox that was condemned to be stoned is also different: if it was exonerated before being stoned, it is sent out to graze with the herd; if after being stoned, one is permitted to benefit from it. A calf whose neck is to be broken is also different: if the murderer was found before the calf’s neck was broken, it is sent out to graze with the herd; if after its neck was broken, it must be buried where it is. Since it was always brought because of a doubt, it still atones for what was in doubt as intended.

Krisos 6:3

Rabbi Eliezer says that one can bring a conditional guilt offering as a freewill offering on any day and at any time that he likes; this is called a “guilt offering of pious people.” People say that Bava ben Buti brought a conditional guilt offering as a freewill offering every day except for the day after Yom Kippur. He exclaimed that he would bring one then, too, if they would let him but they insisted that he wait until he entered a state of doubt. The Sages day that a conditional guilt offering is only brought for something that incurs kareis if done intentionally and a sin offering if done unintentionally (and therefore cannot be brought as a freewill offering).