Temurah 19B

אמר רבי יוסי ברבי חנינא: ומודה רבי אלעזר במפריש נקבה לאשם דאין בנה קרב אשם. פשיטא! עד כאן לא קאמר רבי אלעזר אלא במפריש נקבה לעולה, דאיכא שם עולה על אמו, אבל גבי מפריש נקבה לאשם דליכא שם אשם על אמו ⁠— אפילו רבי אלעזר מודה דלא קרב אשם!

R' Yosei, son of R' Ḥanina, said: And R' Elazar concedes to the opinion of the Rabbis with regard to a case where one designates a female animal for a guilt offering, which is only brought from a male animal, that its offspring is not sacrificed as a guilt offering. The Talmud asks: Isn’t that obvious? As R' Elazar states that the offspring may be sacrificed only if one designates a female animal for a burnt offering and it gives birth, due to the fact that there is burnt offering status for a bird that is the same sex as its mother. But with regard to one who designates a female animal as a guilt offering, where there is no guilt offering status for its mother, even R' Elazar concedes that its offspring is not sacrificed as a guilt offering.

אי לאו דאשמעינן, הוה אמינא טעמא דרבי אלעזר לאו משום דשם עולה על אמו, אלא משום דחזי ולד להקרבה, והאי נמי הא חזי להקרבה, קא משמע לן.

The Talmud answers that this statement is nevertheless necessary, for if R' Yosei, son of R' Ḥanina, had not informed us of this halakha, I would say that the reason for the ruling of R' Elazar, that one who designates a female animal for a burnt offering may sacrifice the offspring as a burnt offering, is not due to the fact that there is burnt offering status for a bird with the same sex as its mother; rather it is because the offspring is fit as an offering, as it is a male, and this too, the offspring of the female that was designated as a guilt offering, is likewise fit as an offering, as it is a male. Therefore, he teaches us that this offspring is not sacrificed even according to the opinion of R' Elazar.