Parsha Mitzvot: Bo: Mitzvah 12 – Concept 278
“If you do not redeem it (the first-born donkey) you shall axe the back of its neck.” (Exodus 13:13) We are commanded to break the neck of the donkey if the owner does not intend to redeem it. (Rambam, Hilchot Bikkurim)
The donkey – “Chamor” – represents “Chomer” – purely physical existence. A person can transform his physical life into spiritual essence. However, if he is stiff-necked, too stubborn to change, his battle will no longer be one of transformation, but of breaking habits and patterns of behavior. (Based on Zohar – Bo)