A man goes to the pastor to buy his horse. The pastor tells him that the horse is a wonderful filly, but has had some unique training. Instead of "giddyup", the horse responds to "Thank God" and instead of "whoa" the horse responds to "Amen". The man agrees that this unique training is okay, since the pastor is selling the horse so cheap.
The next day, the man takes the horse for a run. "Thank God!" he yells and the horse takes off. He can't believe how fast the horse can go, so he tests her limit by yelling "Thank God, Thank God, Thank God!" and the horse moves faster and faster, seemingly without limit. The man is so carried away in the moment he nearly forgets about the nearby gorge and stumbles to get the horse to stop. "Whoa, WHOA!" he yells in vain. Finally he remembers the special word and shouts "AMEN!!" right as the horse stops, not inches from the edge. In a relieved voice, the man pats the horse on the head and says, "Thank god you stopped in time!"