A Groom Mounted on a Chestnut Hunter, He Holds a Bay Hunter by the Reins Jacques-Laurent Agasse (1767-1849)

The picture has something of this: cavalry, people, seated, mammal, horse, two, mare, equestrian, saddle, racehorse, cowman, farm, group, herder, man, rider, grassland, recreation.
Perhaps it’s a painting of a man riding on the back of a brown horse next to.