Aesop’s The Farmer and the Viper
A Farmer walked through his field one cold winter morning. On the ground lay a Snake, stiff and frozen with the cold. The Farmer knew how deadly the Snake could be, and yet he picked it up and put it in his bosom to warm it back to life.
The Snake soon revived, and when it had enough strength, bit the man who had been so kind to it. The bite was deadly and the Farmer felt that he must die. As he drew his last breath, he said to those standing around:
Learn from my fate not to take pity on a scoundrel.