וְהֵבִ֤יא אֹתָם֙ אֶל־הַכֹּהֵ֔ן וְהִקְרִ֛יב אֶת־אֲשֶׁ֥ר לַחַטָּ֖את רִאשׁוֹנָ֑ה וּמָלַ֧ק אֶת־רֹאשׁ֛וֹ מִמּ֥וּל עָרְפּ֖וֹ וְלֹ֥א יַבְדִּֽיל׃
And he shall bring them unto the priest, who shall offer that which is for the sin-offering first, and pinch off its head close by its neck, but shall not divide it asunder.
Shenei Luchot HaBerit
לא יבדיל . Concerning the law not to sever the head of a bird serving as a sin offering (5,8). Rabbi Menachem HaBavli reasons that seeing the sinner had been קשה עורף, stiff-necked vis-a-vis G–d when he committed the sin he now wishes to atone for, this is symbolized by the Torah specifying that he must "pinch the head of this bird at its neck without severing it."