Leviticus 25:21

Then I will command my blessing upon you in the sixth year,.... Upon their fields, vineyards, and oliveyards, and make them exceeding fruitful, more than in other years; all fruitfulness at any time depends upon the blessing of God, and follows upon it, but is more visible and observable when there is an exceeding great plenty:

and it shall bring forth fruit for three years; and thus God blessed the sixth year with such a plentiful increase as was sufficient for time to come, until a new crop was gathered in; as he had blessed the sixth day with a double portion of manna, for the supply of the seventh.