what ("I am rightly served for pitying a scoundrel.") means ?
especially the words (served) and ( for pitying)

the contest is this story:
One winter a Farmer found a Snake stiff and frozen with cold. He had compassion on it, and taking it up, placed it in his bosom. The Snake was quickly revived by the warmth, and resuming its natural instincts, bit its benefactor, inflicting on him a mortal wound. "Oh," cried the Farmer with his last breath, "I am rightly served for pitying a scoundrel."

Question

what ("I am rightly served for pitying a scoundrel.") means ?
especially the words (served) and ( for pitying)

the contest is this story:
One winter a Farmer found a Snake stiff and frozen with cold. He had compassion on it, and taking it up, placed it in his bosom. The Snake was quickly revived by the warmth, and resuming its natural instincts, bit its benefactor, inflicting on him a mortal wound. "Oh," cried the Farmer with his last breath, "I am rightly served for pitying a scoundrel."

Answer

It means I deserved what happened to me as I helped a scoundrel.

Answer

"Served" means that he was the object of an action (here, being bitten).  "Pitying" means that he felt bad for the snake and, as a result of feeling bad, decided to help the snake (which turned out to be a fatal decision).

Answer

Yes, "I am rightly served" means "I deserved what happened to me".

When someone does something wrong, dishonest, selfish or foolish, and then they suffer for their actions, we say "It serves you right!" This means they deserved the result of their own bad behaviour.