TT #363 · Parashas Shoftim · Seventh Aliyah · Passuk 21:04
And the elders of that city shall bring the heifer down to a hard valley that has not been worked and has not been sown, and they shall break the neck of the heifer there in the valley.
Torah Temimah points to Sotah 46b / Sifrei.
TT lemma: וְעָרְפוּ שָׁם אֶת הָעֶגְלָה בַּנָּחַל.
English: ‘And they shall break the neck of the heifer there in the valley’ – with a cleaver.
Derash on the method of arifah (Bavli / Sifrei) — a specific instrument and action are required.
The elders break the heifer’s neck in the valley with a heavy cleaver from behind.