Midrash sa Exodo 21:6: Ein Yaakov (Glick Edition), Mekhilta DeRabbi Yishmael, Midrash Tanchuma & Midrash Tanchuma Buber

(Fol. 23) Our Rabbis were taught (Deut. 15, 16) Because he (the servant) is well with thee; i.e., well with food and well with drinks with you (the employer). This means that thou shalt not eat white bread while thy servant eats dark bread; that thou shalt not drink old wine while thy servant drinks fresh wine; that thou shalt not sleep upon cushions while thy servant sleeps on straw. From this, remarked our Rabbis, we may infer that whoever buys a Hebrew slave, it is as if he were buying a master over himself, (Ib. b) (Ex." 21, 6) And his master shall bore his ear through with an awl, etc. R. Jochanan b. Zakkai interpreted this passage in a symbolical way (giving an ethical signification to the Biblical law about perforating the slave's ear). "Why was the ear chosen to be bored, above all the other members of the body? The Holy One, praised be He! said: 'The ear which heard on Mt. Sinai (Lev. 25, 55) For unto Me are the children of Israel servants, but not servants under servants, and this one went and purchased another master upon himself, therefore must the ear be bored for not remembering what it heard."' (Ex. 21, 6) And he shall bring him at the door, etc. Simon b. Rabbi interpreted this in a symbolical way: "Why was the door and the door-post upon which the slave's ear shall be bored chosen in preference to any other place in the house? The Holy One, praised be He, said: 'The door and the door-post which were witnesses in Egypt at the time when I passed over the lintel and the doorposts, when I said, all the children of Israel are My servants and not servants under servants, for which purpose I have also redeemed them from slavery unto freedom, and this one went and bought a master upon himself, therefore shall his ear be bored before the lintel and the door-posts.'"

"Then his master shall bring him near to elohim": These are the judges, that he might consult those who sold him.

"and he shall bring him near to the door or to the door-post": The door is being compared to the door-post, viz.: Just as a door-post stands in its place, so, the door must be standing in its place. And this would follow a fortiori, viz.: If the door, which is not kasher for the mitzvah (of mezuzah), is kasher for boring, then the door-post, which is kasher for the mitzvah of mezuzah, how much more so should it be kasher for boring! It is, therefore, written (Devarim 15:17) "Then you shall take the awl and place it in his ear and in the door" — You place it in the door, but not in the door-post. But perhaps the awl is to pierce both his ear and the door-post; it is, therefore, written (Exodus 21:6) "then his master shall bore his ear with an awl" — his ear is pierced and not the door. It is the first reading, then, which is to be accepted — The door is being compared to the door-post, viz.: Just as a door-post stands in its place, so, the door must be standing in its place.