Why was the ear selected over any other limb of the body? Rabbi Yochanan ben Zakai explains that, if the ear heard at Har Sinai, “You shall not steal!” and the owner of that ear none- the-less went ahead and stole, his ear should be pierced. Why should the ear be singled out, given that the hands and feet were involved in an act of theft? They should be pierced! It is almost as if the ear was held responsible for the theft. Horav Tzvi Pesach Frank, zl, explains that the Giving of the Torah was not a one-time, isolated experience. Chazal teach that the Torah should be perceived by us as being newly-given every day. This means Hashem’s voice speaks to us anew all of the time: when we take a sefer in hand; when we study Torah, we are hearing the dvar Hashem, word of G-d, as it was heard then.
The sin of the ear is that it heard it once at Har Sinai, and that was it. It was a one-time hearing with no “follow up.” The fact that it did not hear the Lo signov, Do not steal, now, is the reason that the ear is pierced. We may never disconnect from Sinai. Hashem’s voice should resonate within us all of the time. It is when we stop listening to His voice, however, that we also stop doing His will, observing His mitzvos.