What is the origin of the saying "The conveyor of disbelief is not a disbeliever," who said it, and is it considered a jurisprudential principle?

The rule "The transmitter of disbelief is not a disbeliever" is correct if the transmitter merely recounts the disbelief, or recounts and refutes it, as is the case in the Qur’an and Sunnah. However, if he transmits it affirming it or agreeing with it, then he is a disbeliever, just like the one who uttered it. This rule is a matter of creed related to the chapter on declaring someone a disbeliever.