The Serpent and The Cow

Once upon a time, there is a huge serpent alive. The serpent is so big so that can swallow a full grown cow at once. One day the serpent is anxious because there is nothing can satisfy his appetite. So he wander through forest outskirt, and he met an old rat, the rat scared and beg for a mercy, "Oh, mighty lord, I beg you a mercy for this humble old flesh, please do't eat me." "I'm not interested to eat you, old rat, your flesh are not edible anymore", the serpent is waving away.
In another path he met a young cow being tied to tree. The serpent bloat "Why don't you beg for a mercy foolish cow", the cow said "Neither I beg for a mercy, I would be eaten by human next day." The serpent stop and watch the cow carefully "How could that be ? Human made your kin work for them right ? And eat your flesh too ? Are you trying to make fun of me ?" The serpent lost it's patience and twisted the cow. The cow was swallowed at once. The human stabbed the serpent with along spear and after a few days suffer, the serpent dead.