'Worker' in the Bible

You should not consider it difficult to let him go free, for he will have served you for six years, twice the time of a hired worker; the Lord your God will bless you in everything you do.

Suppose he goes with someone else to the forest to cut wood and when he raises the ax to cut the tree, the ax head flies loose from the handle and strikes his fellow worker so hard that he dies. The person responsible may then flee to one of these cities to save himself.