Sir 5:12

“"When they found him on the other side of the sea, they said to him, 'Rabbi, when did you come here?' " The episode has the aspects of a scene between friends and expresses something delicate. However, some elements seem rather senseless and childish. They should not, in fact, have followed such a great teacher only to talk about frivolous things instead of asking to learn something. What need was there to ask when he had arrived? Or what advantage would have resulted from knowing? We must then seek wisdom from the wise and let a prudent silence be preferred over inept speeches. For the apostle exhorts us to flavor our speech with salt, and another of the wise invites us with similar words: "If you have understanding, answer your neighbor; but if you do not, put your hand on your mouth." And we also learn from another place how evil it is to be condemned for any recklessness of language: "If any one thinks he is religious, and does not bridle his tongue, but deceives his heart, this man's religion is vain."”

“"If you have understanding, answer your neighbor; if not, let your hand be over your mouth." Prudential understanding teaches what is to be carried out, namely every good, according to the way of interior thought and exterior action. God wills that we do all things reasonably. And blessed Ambrose says that we ought neither to do nor to speak anything about that for which we cannot give a reason.”