Change One Letter

Riddle: There is one word in the English language which is universally considered a preventive of harm; change a certain letter in it, and you make it an act of cruelty. What are the words?

Answer: Prescription—proscription. Source: https://riddles.com/index.php/906

There is one word in the English language which is universally considered a preventive of harm; change a certain letter in it, and you make it an act of cruelty. What are the words? — Change one letter by Anonymous Riddle