Мусар к Мишлей 27:14

They, may their memory be blessed, also mentioned and said about the content of the dust of evil speech (Arakhin 15b) [that] if a woman asked her neighbor to [light a fire] from the hearth, and she answers and says, “Where else is a fire of coals except at so-and-so’s home, who is always roasting meat and eating” - this and what is similar to it is the dust of evil speech. And it is stated (Proverbs 27:14), “He who greets his fellow loudly early in the morning shall have it reckoned to him as a curse.” And our Rabbis explained (Arakhin 16a) this verse about someone who praises his fellow with a praise that brings a loss, to be about a guest who goes out to the town square and calls out in a loud voice and recounts how the householder did him good - since he [prepared] meat and made it for the guest that came to him. But it would be that when they hear the words of the guests, worthless people will assemble and turn aside to the home of the householder. And a person is obligated to guard his mouth and his tongue, such that he not be suspected about his words and that they not account him to be one involved in evil speech. And if he does bring such a suspicion about himself with this, he has surely destroyed his ethical [standing], and it will be considered the dust of evil speech for him.

One must be very careful with the blessing of God, not to recite a blessing in vain or an unnecessary blessing. For [if he does so], he transgresses, "You shall not take [the Lord, your God's name in vain" (Exodus 20:7). And you find this with an ignoramus who wants to be pious and recites a blessing over every single thing; and they sometimes stumble and fall with the prohibition of a blessing in vain or an unnecessary blessing. 'So the one who walks with the Sages will become wise.' And likewise concerning blessing (greeting) one's friend, it is written (Proverbs 27:14), "He who greets his fellow loudly early in the morning shall have it reckoned to him as a curse." And there are two ways this [happens]. The first is that there is a prohibition to say hello to one's fellow or to greet him before prayer [in the morning] since it is considered as if he is making him into an altar. And the second way is if he greets his friend in front of others and causes evil to [his friend], as the others will jump on him, since they will think that it would be fitting and good that he benefits them much more than he benefits this one. But [his fellow] does not imagine it so, and his heart does not think so for various reasons known to him. So it comes out that he caused for there to be arguments and grudges against him. Hence, 'every clever man should act knowledgeably.' So in any place where there is a concern that some damage will be caused to his fellow in any aspect or way - if he knows the thing, 'a trustworthy soul keeps a confidence.'

But there are times when the Sages permitted one to lie, for example, in order to make peace between one man and another (Yebamoth 65b). Similarly, one may praise a bride in the presence of the bridegroom and say that she is lovely and charming, even though she really is not (Kethuboth 17a). A guest (Arakin 16a) who has been well treated by the master of the house should not to say in front of many people, "How good that man is in whose house I was a guest, how much honor he paid me," lest many come to that host who are not worthy to be his guests, and concerning this it is said, "He that blesseth his friend with a loud voice, rising early in the morning, it shall be counted as a curse to him" (Prov. 27:14).