Leviticus 25:20-22

20And if you say, 'What shall we eat in the seventh year, if we may not sow or gather in our crop?'

21I will command my blessing on you in the sixth year, so that it will produce a crop sufficient for three years.

22When you sow in the eighth year, you will be eating some of the old crop; you shall eat the old until the ninth year, when its crop arrives.