If any one take over a waste-lying field to make it arable, but is lazy, and does not make it arable, he shall plow the fallow field in the fourth year, harrow it and till it, and give it back to its owner, and for each ten gan (a measure of area) ten gur of grain shall be paid.
Thief of Time (allthetropes.org)Thief of Time is the 26th Discworld novel and the fifth in the Death/Susan theme, although it also feels like something of a standalone.