ורצע אדניו את אזנו במרצע…(משפטים כא:ו)

Rashi says that the reason for this kind of punishment is as follows: the ear that heard at Har Sinai the commandment of not stealing, and this thief disregarded this prohibition and stole such an ear needs to be pierced.

We need to understand why it is the ear’s fault if the hand stole.  One needs to look at the root cause: if someone doesn’t comply with what he hears, his ear must be punished.