Exodus 23:10,11

And six years thou shalt sow thy land, and shalt gather in the fruits thereof: Six years thou shalt sow - intermitting the cultivation of the land every seventh year. But it appears that even then there was a spontaneous produce which the poor were permitted freely to gather for their use; and what they did not eat was to be left as a feast to the lower animals, wild beasts, birds, and insects, the owners of fields not being allowed to reap or collect the fruits of the vineyard or oliveyard during the course of this Sabbatical year.

This was a regulation subservient to many excellent purposes; for, besides inculcating the general lesson of dependence on Providence, and of confidence in His faithfulness to His promise respecting the triple increase on the sixth year (Leviticus 25:20), it gave the Israelites a practical proof that they held their properties of the Lord as His tenants, and must conform to His rules, on pain of forfeiting the lease of them.