If a Jewish servant does not wish to go free after six years of servitude, his master brings him before the court and pierces his ear in the presence of the judges. The servant may then remain with his master until the Yovel, the Jubilee year.
Why does the Torah single out the servant’s ear for piercing, out of all the other limbs of the body? The Talmud explains: For the Almighty says: This ear, which heard My voice on Mount Sinai when I proclaimed, ‘For Bnei Yisrael are slaves to Me’—they are My servants, and not servants of servants, and yet went and acquired a master for himself, let it be pierced!
But was the revelation at Sinai only heard, not seen? Doesn’t the Torah say, “And the entire nation saw the sounds”?
If the servant’s ears are guilty for not abiding by what they heard, why aren’t his eyes held accountable for not living up to what they witnessed?
In truth, however, the Torah’s “disappointment” with the servant is not that he is less spiritually sensitive than he was at Sinai, when he heard and saw the voice of G-d. The disappointment is that he is not living up to his current potential, based on what he experienced at Sinai. And therein lies the difference between what he saw and what he heard.
After the sounding of the Ten Commandments, the awesome G-dly revelation at Sinai ceased. Hence, a Jew can no longer be expected to relate to G-d on the level of “seeing,” with the clarity of purpose that Bnei Yisrael had during the revelation at Sinai.
The purpose of this post-Sinai concealment, however, was to allow Bnei Yisrael to arrive at accepting the yoke of G-d on their own accord. Meaning, that our ability to “hear,” i.e., to choose to be G-d’s subjects even when His presence is concealed, is still intact. Accordingly, we are held accountable, even post-Sinai, if we fail to hear and recognize that “Bnei Yisrael are slaves to Me,” and not “servants to servants.”
—Toras Menachem, vol. 39, pp. 110–113