Leviticus 25:2-4

Speak unto the children of Israel, and say unto them, When ye come into the land which I give you, then shall the land keep a sabbath unto Jehovah. Six years thou shalt sow thy field, and six years thou shalt prune thy vineyard, and gather in the fruits thereof; but in the seventh year shall be a sabbath of solemn rest for the land, a sabbath unto Jehovah: thou shalt neither sow thy field, nor prune thy vineyard.