Keritot 27B

מתני׳ המפריש חטאתו ומת ⁠– לא יביאנו בנו תחתיו. לא יביאנו מחטא אל חטא. אפילו הפריש על חלב שאכל אמש ⁠– לא יביאנה על חלב שאכל היום, שנאמר: ״קרבנו על חטאתו״⁠ – עד שיהא קרבנו לשם חטאתו.

Mishnah: In the case of one who designates a sin offering for his performance of an unwitting sin and dies, his son should not bring it in his stead, neither on behalf of his father nor for his own unwitting sin, even if it was the same transgression. Likewise, one may not bring a sin offering by reassigning it from the sin for which it is designated to atone and sacrificing it for atonement of another sin. Even if he designated a sin offering as atonement for forbidden fat that he unwittingly ate yesterday, he may not bring it as atonement for forbidden fat that he unwittingly ate today, as it is stated: “And he should bring his sin offering, an unblemished female goat, for his sin that he has sinned” (Leviticus 4:28), indicating that he does not satisfy his obligation until his offering is brought for the sake of the sin for which he designated it.

גמ׳ מנא הני מילי? דתנו רבנן: ״קרבנו״⁠ – בקרבנו הוא יוצא, ואינו יוצא בקרבן אביו.

Talmud: The Talmud asks: From where is this matter, i.e., that a son may not bring his father’s sin offering, derived? The Talmud answers that it is derived as A baraita states: The Torah states with regard to a sin offering: “And he should bring for his offering” (Leviticus 4:23). This indicates that one fulfills his obligation with his own offering, but he does not fulfill his obligation with his father’s offering, if his father was obligated to bring a sin offering and died after he designated an animal for this purpose.