Leviticus 25:20-22

But you might ask, ‘What will we eat during the seventh year, since we are not allowed to plant or harvest crops that year?’ Be assured that I will send my blessing for you in the sixth year, so the land will produce a crop large enough for three years. When you plant your fields in the eighth year, you will still be eating from the large crop of the sixth year. In fact, you will still be eating from that large crop when the new crop is harvested in the ninth year.