What does it mean for a farmer to pity a snake for being bitten by a snake and set the tiger back to the mountain to hurt people?

The farmer pities the snake for being bitten by a snake, and releasing the tiger to the mountain is to bite the hand that feeds him. According to relevant information, the general meaning of farmer and snake is that after a kind person saved a snake, the snake killed the benefactor who saved it. This is called biting back, which means the same thing as letting the tiger go back to the mountain and hurting people. Now it is often used to describe people who are not grateful. After being helped, they not only don't know how to thank others for their help, but think about how to kill their benefactors. Seeing that such people should stay away, they can never help.