אַ֣ךְ בְּֽכוֹר־שׁ֡וֹר אֽוֹ־בְכ֨וֹר כֶּ֜שֶׂב אֽוֹ־בְכ֥וֹר עֵ֛ז לֹ֥א תִפְדֶּ֖ה קֹ֣דֶשׁ הֵ֑ם אֶת־דָּמָ֞ם תִּזְרֹ֤ק עַל־הַמִּזְבֵּ֙חַ֙ וְאֶת־חֶלְבָּ֣ם תַּקְטִ֔יר אִשֶּׁ֛ה לְרֵ֥יחַ נִיחֹ֖חַ לַֽיהוָֽה׃
오직 소의 처음 난 것이나 양의 처음 난 것이나 염소의 처음 난 것은 속하지 말지니 그것들은 거룩한즉 그 피는 단에 뿌리고 그 기름은 불살라 여호와께 향기로운 화제로 드릴 것이며
Mishneh Torah, Firstlings
A sheep that gave birth to offspring similar to a goat, or a goat that gave birth to offspring similar to a sheep, it is exempt from firstborn laws, as it says (Numbers 18, 17): "Just the firstborn of an ox", only when it is an ox and its eldest son is an ox. And if it had some signs of its mother it is a firstborn and it is permanently blemished for there is no blemish greater than change of its species. Even a cow that gave birth to offspring similar to a donkey, and it has some signs of a cow, it is a firstborn for the priest because the laws of firstborn apply to donkeys. But if it gave birth to [offspring similar to] a horse or a camel, even if it has some signs of a cow, it is a doubtful firstborn and therefore may be eaten by the owners. And if the priest seized it, we don't take it from him [the priest].
Mishneh Torah, Overview of Mishneh Torah Contents
LAWS OF THE FIRST-BORN.
These comprise five precepts, of which two are affirmative precepts and three are negative precepts. Their detailed enumeration is as follows: 1) to set apart the first-born (of the cattle); 2) not to eat an unblemished first-born outside Jerusalem; 3) not to redeem the first-born (of the clean cattle); 4) to set apart tithe of the young of the clean cattle; 5) not to redeem the tithe of cattle. I have included the laws of tithe of cattle with those of first-born of cattle because the procedure is the same in both, and Scripture includes the former with the latter in the text "Thou shalt sprinkle their blood (on the altar)" (Num. 18:17), which text has been traditionally interpreted to refer to the blood of the tithe of cattle and the blood of firstlings.
These comprise five precepts, of which two are affirmative precepts and three are negative precepts. Their detailed enumeration is as follows: 1) to set apart the first-born (of the cattle); 2) not to eat an unblemished first-born outside Jerusalem; 3) not to redeem the first-born (of the clean cattle); 4) to set apart tithe of the young of the clean cattle; 5) not to redeem the tithe of cattle. I have included the laws of tithe of cattle with those of first-born of cattle because the procedure is the same in both, and Scripture includes the former with the latter in the text "Thou shalt sprinkle their blood (on the altar)" (Num. 18:17), which text has been traditionally interpreted to refer to the blood of the tithe of cattle and the blood of firstlings.
Mishneh Torah, Negative Mitzvot
Not to exchange a beast set aside for sacrifice, as it is said, “He shall not alter it nor change it” (Lev. 27:10).