This beautiful stone relief from the 10th century BC shows an Aramaean warrior on horseback. The way the rider's hand is held makes the horse's leap seem playful, though I think it is simply a composition decision to prevent the arm overlapping the horse's neck or the rider's other arm, which holds a whip. I think the horse looks like it is smiling slightly, which adds to the playful impression I get, although if you enlarge the image you can see that the rider certainly isn't smiling, just the horse! Go to The British Museum site to see a large image and a detailed description of the origins and significance of this piece.
Photo: The British Museum website