Leviticus 25:21

“Then I will command my blessing upon you in the sixth year, etc.] 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.”

“I will command my blessing upon you in the sixth year, and it shall bring forth fruit for three years, &c.--A provision was made, by the special interposition of God, to supply the deficiency of food which would otherwise have resulted from the suspension of all labor during the sabbatic year. The sixth year was to yield a miraculous supply for three continuous years. And the remark is applicable to the year of Jubilee as well as the sabbatic year. (See allusions to this extraordinary provision in Kg2 19:29; Isa 37:30). None but a legislator who was conscious of acting under divine authority would have staked his character on so singular an enactment as that of the sabbatic year; and none…”

“For three years - Not compleatly, but in great part, namely, for that part of the 6th year which was between the beginning of harvest and the beginning of the 7th year, for the whole 7th year, and for that part of the 8th year which was before the harvest, which reached almost until the beginning of the ninth year. This is added to shew the equity of this command. As God would hereby try their faith and obedience, so he gave them an eminent proof of his own exact providence and tender care over them in making provisions suitable to their necessities. Leviticus 25:22”

“I will: As it is here graciously promised, that the sixth year was to bring forth fruits for three years, not merely for two, it is evident that both the sabbatical year and the year of jubilee were distinctly provided for. They were not to sow from the sixth to the eighth year, omitting two seed times; nor reap from the sixth to the ninth, omitting two harvests. No legislator, unless conscious of being divinely commissioned, would have committed himself by enacting such a law as this; nor would any people have submitted to receive it, except in consequence of the fullest conviction that a divine authority had dictated it. It therefore stands as a proof that Moses acted by the express…”