Leviticus 25:8-10

8“You are to count off seven Shabbatot of years—seven times seven years, so that the time is seven Shabbatot of years—49 years.

9Then on the tenth day of the seventh month, on Yom Kippur, you are to sound a shofar blast—you are to sound the shofar all throughout your land.

10You are to make the fiftieth year holy, and proclaim liberty throughout the land to all its inhabitants. It is to be a Jubilee to you, when each of you is to return to his own property and each of you is to return to his family.