I often wonder if the Lord had in mind our standing in Grace when he instituted this law. For six years (six meaning flesh) the land was to be worked, but on the seventh (rest), the land was given respite. Similarly, God worked to create the world in 6 days and rested on the 7th. (Of course, we know that God could have made the heavens and the earth in 1 day - or one second - and would have never needed to rest.) Hebrews 4 sheds light on such passages. Under the law, we worked for our righteous standing. In grace we rest, knowing Jesus has already earned righteousness standing for us.

Leviticus 25:4