Musar zu Ijow 13:5

But there are times when silence can be evil, as it is written, "Answer a fool according to his folly, lest he be wise in his own eyes" (Prov. 26:5). With respect to words of the Torah, if a person sees that the fools are scorning the words of the wise, he should answer in order to turn them back from their errors so that they do not imagine themselves wise in their eyes. If a man sees another man committing a transgression, he should protest and reprove him. And long ago Solomon said, "A soft answer turneth away wrath" (Prov. 15:1), "and a soft tongue breaketh the bone" (Prov. 25:15). Therefore, a man should accustom himself to speak gently and not harshly. And be careful to guard your tongue like the apple of your eye, for "A fool's mouth is his ruin, and his lips are the snare of his soul" (Prov. 18:7). And it is further written, "Whoso keepeth his mouth and his tongue keepeth his soul from troubles" (Prov. 21:23). And it is said, "Oh, that ye would altogether hold your peace! And it would be your wisdom" (Job 13:5). And if you are sitting in a group, it is better that they should say to you, "Speak, why are you so silent?" than that you should speak and your words become such a burden to them that they finally say to you, "Be silent!"