If you buy a Hebrew servant, he is to serve you for six years. But in the seventh year, he shall go free, without paying anything. If he comes alone, he is to go free alone; but if he has a wife when he comes, she is to go with him. If his master gives him a wife and she bears him sons or daughters, the woman and her children shall belong to her master, and only the man shall go free.
But if the servant declares, 'I love my master and my wife and children and do not want to go free,' then his master must take him before the judges. He shall take him to the door or the doorpost and pierce his ear with an awl. Then he will be his servant for life.
If a man sells his daughter as a servant, she is not to go free as menservants do.
~ Exodus 21:2-7, NIV