John Calvin Commentary Leviticus 25:8

"And thou shalt number seven sabbaths of years unto thee, seven times seven years; and there shall be unto thee the days of seven sabbaths of years, even forty and nine years." — Leviticus 25:8 (ASV)

And you shall number seven. The third kind of Sabbath follows, which was composed of forty-nine, or seven times seven years.

This was the most illustrious Sabbath, since the state of the people—regarding their persons, houses, and property—was renewed. Although in this way God considered the public good, gave relief to the poor so that their liberty would not be destroyed, and also preserved the order He Himself had established, there is no doubt that He thus added an additional stimulus to incite the Jews to honor the Sabbath.

For it was a kind of imposing memorial of the sacred rest to see slaves emancipated and become suddenly free, houses and lands returning to their former possessors who had sold them, and, in short, all things taking on a new appearance.

They called this year Jobel, from the sound of the ram’s horn by which liberty and the restitution of property were proclaimed. But as I have said, its main feature was the solemnity that showed them to be separated from other nations, to be a peculiar and holy nation to God. Indeed, the renewal of all things was related to this: that, being redeemed anew in the great Sabbath, they might entirely devote themselves to God their Deliverer.