A guy needed a horse, so he went to a temple and got one. Before he left, the priest told him that it was a special horse. In order for it to go, he would say Thank God and for it to stop he would have to say Amen.
So the guy went, and a few minutes later he dozed off on his horse. A few hours later, he woke up and was going off the edge of a cliff. So he shouted Amen! and the horse stopped a few inches from the edge.