The Torah tells us "ורצע אדניו את אזנו במרצע ועבדו לעלם". Rashi makes a point of noting that the servant’s ear in question is the right ear, and not the left and he goes to great lengths to prove this point. 

     But The Rebbe R’ Heschel of Krakow zt"l in Chanukas HaTorah asks that despite Rashi's proofs, why would we even think for a moment that the posuk is referring specifically to the left ear as opposed to either one? He explains that the reason is because as Chazal tell us, the slave’s ear is bored through due to the fact that ‘the ear that heard at Sinai the words, Thou shall not steal, and he went and stole, deserves to be bored.’ 

     The Medrash states in the name of Rabban Shimon bar Yochai that when Hashem spoke to the Nation at Har Sinai, the words went out ‘from the right of Hashem to the left of Yisroel.’ It turns out, therefore, that the ear that heard Hashem’s words was the left ear! In case one might think the left ear is bored, Rashi proves otherwise!