Parashas Bo · Passuk 13:13
Chabad.org — English translation + Rashi
Torah Temimah points to Bekhoros 10b (verified).
English: It is said here “breaking the neck” and regarding the eglah arufah “breaking the neck” — just as the eglah arufah is forbidden in benefit, so the firstling donkey is forbidden in benefit.
In context: See the cited source for the full section.
Derash on the verse.
A peter chamor that was killed by arifah is forbidden in benefit.