Midrash su Deuteronomio 21:9

7) (Vayikra 7:24) "lo tochluhu": I might think this means that he shall not feed it to others (non-Jews). It is, therefore, written (Vayikra 7:24) "ve'achol" — You may feed it to others. But perhaps "ve'achol" signifies that cheilev from which benefit may be derived is clean (of neveilah-tumah and may be used for all service), but the cheilev of an ox that was stoned, and that of an eglah arufah (the heifer of the broken neck, Devarim 21:1-9, [if it died before its mitzvah was performed]), from which benefit may not be derived, is not clean (of neveilah-tumah). It is, therefore, written (Devarim 21:9) (the redundant) "and the cheilev … and the cheilev" (to include the cheilev of the foregoing as permitted for all use).