bor: According to the Book of the Covenant (Ex 20:20 through Ex 23:33) a slave whom his master had purchased was to be released after six years. Should he choose to remain in his master's service a religious ceremony was necessary to ratify his decision. "Then his master shall bring him unto God" (better than "unto the judges" of the King James Version), "and shall bring him to the door, or unto the doorpost; and his master shall bore his ear through with an awl" (Ex 21:6). It is highly improbable that "unto God" means "to a sanctuary"; for there was no special reason for performing this ceremony near the door of a sanctuary. On the other hand the entrance to a private house was a sacred spot. According to primitive thinking near the door dwelt the household gods whose function it was to guard the house and its occupants, e.g. against the entry of disease. It was natural that the ceremony of attaching the slave permanently to the master's household should be performed in the presence of the household gods. "The boring of the ear of slaves was a common practice in antiquity, possibly to symbolize the duty of obedience, as the ear was the organ of hearing" (Bennett). The Deuteronomist (De 15:17) rejects the religious aspect of the ceremony--probably as a relic of Canaanite religion--and looks upon it as a secular and symbolical operation. According to his view, the awl was thrust through the ear of the slave to the door. The slave in question was permanently attached to the household.
⇒See the definition of bore in the KJV Dictionary