Back to Novigrad
If you go over the bridge on the eastern side of Oxenfurt and follow the path to the south you’ll come across a man by a hut calling out for help. Talk to him to find out that recently his and his neighbour’s horses have been going missing.
Go to the horses pen and use your Witcher senses to take a look around. Follow the tracks to a Scoia’tael camp. They’ve been stealing the horses to carry their wounded.
At this point you can either threaten to take the horse which will result in a fight with all four Scoia’tael, use Axii on the Commander or pay him 100 Crowns.
Either way select one of the horses and ride it back to the man. If it was the correct horse he’ll pay you 20 Crowns for it. If you selected the wrong horse he’ll pay you even more, 50 Crowns, as his horse was old but you’ve brought him a younger horse.