Titus 2:7-8

And show your own self in all respects to be a pattern and a model of good deeds and works, teaching what is unadulterated, showing gravity [having the strictest regard for truth and purity of motive], with dignity and seriousness. And let your instruction be sound and fit and wise and wholesome, vigorous and irrefutable and above censure, so that the opponent may be put to shame, finding nothing discrediting or evil to say about us.