כָּֽל־הַבְּכ֡וֹר אֲשֶׁר֩ יִוָּלֵ֨ד בִּבְקָרְךָ֤ וּבְצֹֽאנְךָ֙ הַזָּכָ֔ר תַּקְדִּ֖ישׁ לַיהוָ֣ה אֱלֹהֶ֑יךָ לֹ֤א תַעֲבֹד֙ בִּבְכֹ֣ר שׁוֹרֶ֔ךָ וְלֹ֥א תָגֹ֖ז בְּכ֥וֹר צֹאנֶֽךָ׃
你牛群羊群中所生的一切頭生的公畜，你都要分別為聖，歸給永恆者你的上帝。不可用頭生的牛耕作，也不可剪頭生的羊的毛。
Sha'arei Teshuvah
“You must not work your firstling ox or shear your firstling sheep” (Deuteronomy 15:19). [The law of] the firstborn is practiced both in the Land [of Israel] and outside the Land. And a firstling that is mixed in a hundred or [even] a thousand (other animals) renders all of them prohibited in benefit.