"No weapon that is formed against thee shall prosper" is the slightly different wording used in the authorized Cambridge edition of the King James Bible. Isaiah 54:17 is the specific chapter and verse where this line is found.
"And every tongue that shall rise against thee in judgment thou shalt condemn" is the line that follows. This passage attests to the power of faith, assuring the faithful of protection from sharp tongues as well as brute force. Believers find strength and comfort in reciting this verse from Isaiah. It promises that God is in control so there is nothing to fear.