Deuteronomy 15:21 (KJV)

And it shall be, if he say unto thee, I will not go away from thee; because he loveth thee and thine house, because he is well with thee;

Then thou shalt take an aul, and thrust it through his ear unto the door, and he shall be thy servant for ever. And also unto thy maidservant thou shalt do likewise.

It shall not seem hard unto thee, when thou sendest him away free from thee; for he hath been worth a double hired servant to thee, in serving thee six years: and the LORD thy God shall bless thee in all that thou doest.

All the firstling males that come of thy herd and of thy flock thou shalt sanctify unto the LORD thy God: thou shalt do no work with the firstling of thy bullock, nor shear the firstling of thy sheep.

Thou shalt eat it before the LORD thy God year by year in the place which the LORD shall choose, thou and thy household.

Thou shalt eat it within thy gates: the unclean and the clean person shall eat it alike, as the roebuck, and as the hart.

Only thou shalt not eat the blood thereof; thou shalt pour it upon the ground as water.