This testimony is true. Therefore, rebuke them sharply, so that they will be sound in the faith
All who spoke in the church needed to present true and pure doctrine. Any who fell short of that were to be rebuked.
We too must be careful to speak the truth. Of course, the only way to speak the truth is to know the truth and so we need to study and memorize God`s Word - just as we are doing.
LeRoy Eims on the importance of Scripture memory: "I think two of the master strokes of the devil have been to convince people he doesn't exist, and that Scripture memory is only for children. He remembers the humility of defeat when Jesus Christ, who was tempted in all points like as we are, met him with the Word of God." (What Every Christian Should Know About Growing; p. 26-27)