Qawl bi-l-mūjib turns a feature of another speaker’s words to a purpose different from the one that speaker intended. The reply may appear to accept a word or description while leaving the original argument without its intended force.
This is not mere repetition or unconditional agreement. Its effect depends upon retaining an aspect of the opponent’s wording while redirecting the underlying claim.
The classical discussion gives two principal forms: transferring an attributed quality to another subject, and taking an expression in a different meaning that its wording can bear.