Deuteronomy 14:28

After three years thou shalt bring out all the tithes of thy fruits, in that year thou shalt lay it up in thy cities.

At the end of three years thou shalt bring forth all the tithe of thine increase the same year, and shalt lay it up within thy gates:

At the end of every three years you shall bring all the tithe of your increase in the same year, and shall store it within your gates.