Exodus 21:2 KJV

If thou buy an Hebrew servant, six years he shall serve: and in the seventh he shall go out free for nothing.
Exodus 21:2, King James Version

In context

1 Now these are the judgments which thou shalt set before them.

2 If thou buy an Hebrew servant, six years he shall serve: and in the seventh he shall go out free for nothing.

3 If he came in by himself, he shall go out by himself: if he were married, then his wife shall go out with him.