The farthing is a monetary unit used in southern Redania. In particular, in Oxenfurt.
“
'Teeth extracted! Almost painless! Cheap, very cheap!'
'What do you mean by cheap?' Dandilion was curious as he bit into a stick-skewered squid as tough as a boot.
'Two farthings an hour!'”
— pg(s). 192, Blood of Elves (UK edition)