The Moral of this story is "Greed is the root of all Evil"...in other words, "Death" didn't even need to be at the Tree, all "Death" needed to leave gold there because he knew that they would kill each other for the gold.
What Is The Moral Lesson To The Pardoner's Tale?
Chaucer's Pardoner, a corrupt man but a gifted preacher, tells a harrowing tale to illustrate the evils of avarice. Three young men are drinking and gambling in a tavern when a messenger arrives to tell them that a friend has been taken "by Death." The drunkards resolve to find Death and kill him. On the way they meet an old man whom they address rudely, mocking his withered apearance. The old man politely explains that he is under a spell and cannot die. He tells them that they will find Death under a nearby tree. Reaching the tree, they find a chest of gold. They agree that the youngest will ride to town, get food and wine, and after dark they will take the treasure home. The youngest brings back wine spiked with rat poison; when he arrives his two companions, as planned, attack and kill him. Then they sit down to drink the wine…