Leviticus 25:20-22

20And if ye say, What shall we eat in the seventh year? behold, we may not sow, nor gather in our produce;

21then I will command my blessing upon you in the sixth year, that it may bring forth produce for three years;

22and ye shall sow in the eighth year, and ye shall eat of the old fruit until the ninth year; until her produce come in, ye shall eat the old.