10 And six years thou shalt sow thy land, and shalt gather in the fruits thereof:
11 But the seventh year thou shalt let it rest and lie still; that the poor of thy people may eat: and what they leave the beasts of the field shall eat. In like manner thou shalt deal with thy vineyard, and with thy oliveyard.
12 Six days thou shalt do thy work, and on the seventh day thou shalt rest: that thine ox and thine ass may rest, and the son of thy handmaid, and the stranger, may be refreshed.
Today the laws of the sabbath are expanded and we are given the concept of a sabbath year, which is that after six years of working the field, then the field must be left to rest for the seventh. This is actually very practical, as sowing the same land over and over will take out all of its nutrients, and giving it a rest year to replenish those nutrients is better in the long run.
Of course, the land might naturally produce even without sowing. Vines and trees would continue to produce their grapes and their olives, and these were to be left for the poor and the animals. One can see why Jesus would later reprove the Pharisees for missing the point of the sabbath. From these verses it is clear that the sabbath was for the people, not the people for the sabbath.
Of course, for the owner of the field, having a year of no productivity would require an act of faith. When the Israelites were given manna they were told that God would allow them a double portion on the day before the sabbath, so they wouldn’t have to gather on the rest day. Once again, the owner of the field would have to trust that God would provide enough surplus in the six other years that he could rely on what he had stored up through the seventh. The Israelite might pursue his own wealth and ambition, but every seventh year he would be drawn back to remember his constant dependence on the Lord.