Temurah 5:1 - 5:2

כיצד מערימין על הבכור – to cancel the obligation/release it (i.e., the firstling) from the Kohen and to sacrifice it for his own obligation.

ילדה זכר יקרב עולה – for a firstling is not holy other than in the womb, and since ab initio, it takes effect in another holiness, furthermore, the holiness of its being a firstling no long takes effect with it.

ואם נקבה זבחי שלמים – we are not speaking about a female beast, for the female is not holy with the firstling that one needs to make a deception on it. But the sanctified beast, that if it is sin-offering and she became pregnant and one wants to make a deception so that it will not go to die, for the offspring of a sin-offering goes to its death, one can change it it to another sanctity. [And this comes to inform us] that the offspring of Holy Things, while they are born holy and not in the wombs of their mother, for since they had not yet been sanctified with the holiness of their mothers, one is able to engraft upon them another holiness, so that when they are born, they will not be a sin-offering.

ילדה שני זכרים – we are speaking about an unconsecrated animal, if the animal was dedicated, how was something that was sanctified as a burnt-offering let it be a burnt-offering, for the other one refers to the sanctity of its mother. But it is certainly an unconsecrated animal, and therefore, this one whose monetary value was not sanctified is unconsecrated. But however, on both of them, the holiness of a burnt-offering exists. For since he stated that if [he born animal] is a male, it is a burnt-offering, and because he did not vow other than for one, therefore, he should offer the one for his vow, and the second he should sell for the needs of a burnt-offering and its monetary value/worth is unconsecrated.

אין קדושה חלה עליהן – for the offspring become holy because they are holy [at the time of their existence] and not from the belly of their mother, and since that these when they leave [their mother’s womb] are not appropriate for sacrifice, they are not holy. But the Sages dispute Rabban Shimon ben Gamaliel as they hold that the offspring are holy and exist through the holiness of their mother [from the womb]. And the Halakha is not according to Rabban Shimon ben Gamaliel (see Talmud Temurah 25a).