Verses Lv23-08 discussing the Jubillee year states And you shall count seven sabbath years to you, seven times seven years; and the space of the seven sabbaths of years shall be to you forty and nine years. Rashi explains the underlined phrase sabbath years by citing a nearby reference Lv25-02:04 which describes the land sabbatical: Speak to the people of Israel, and say to them, When you come into the land which I give you, then shall the land keep a sabbath to the Lord. Six years you shall sow your field, and six years you shall prune your vineyard, and gather in its fruit; But in the seventh year shall be a sabbath of rest to the land, a sabbath for the Lord; you shall not sow your field, nor prune your vineyard. Hence the Rashi comment: The sabbath year refers to the earlier mentioned land sabbatical during which no agriculture is done.