Musar su Salmi 73:9

And the fifth is that evil speech brings one involved with it to put his mouth to speaking wrongly about God - and as it is stated (Psalms 73:9), “They set their mouths against Heaven, and their tongues range over the earth.” And there is none among all of the sins the punishment for which reaches the punishment for flinging [accusations at God]. And our Rabbis said (Arakhin 15a), “Our ancestors tried the Holy One, Blessed be He with ten trials, but their sentence was sealed only due to the evil speech.” For it is stated (Numbers 14:28), “I will do to you just as you have urged Me, etc.”; and it is stated (Deuteronomy 1:34), “When the Lord heard your loud complaint, He was angry; and He vowed”; and it is stated (Malachi 2:17), “You have wearied the Lord with your talk.” And King David, peace be upon him, said (Psalms 50:16-20), “And to the wicked, God said, ‘Who are you to recite My laws, and mouth the terms of My covenant. [...] When you see a thief, you fall in with him, etc. You devote your mouth to evil, and yoke your tongue to deceit. You are busy maligning your brother.’“ Behold you have learned from this that Torah [study] does not protect those involved with evil speech or one accustomed to steal or to engage in forbidden sexual relations; and that they are not fit to be involved with Torah. And our Rabbis, may their memory be blessed, said (Sotah 21a) [that] because Doeg spoke evil speech, his wisdom did not stand him in. And that which our Rabbis, may their memory be blessed, said - “Sin extinguishes a commandment, but sin does not extinguish Torah, as it is stated (Proverbs 6:23), ‘For the commandment is a lamp, and the Torah is a light’” - they said about someone who sins by chance, and not about one who removes the yoke of the warning of a sin from upon him.

How much must a man shudder when he remembers that his sins have reached until the holy of holies. And, in truth, we find the likes of this in Tanna d'bei Eliyahu, that the lashon hara that a man speaks rises until the throne of glory, as it is written (Psalms 73:9): "They have set their mouth in the heavens, and their tongue walks the earth."

The ninth quality is the mockery of the scorners and the contempt of the revilers. A man cannot enter upon the service of God until he resolves not to pay any attention to those who may mock him and shame him. If they say of him that he is a flatterer and a hypocrite, he should pay no attention to their words but should consider that if all men were to pay heed to the scornful laughter of the mockers and to the shame of the revilers, no one would do anything good, nor fulfill a commandment, nor do an act of kindness. For no one can save himself from the language of the violent people, as it is said (Psalms 73:9), “They have set their mouth against the heavens and their tongue walketh through the earth.” How many scoffers there are whose mockery arises from jealousy and the desire to abuse. For they recognize the superiority of the one they attack, and they cannot attain his qualities, and because of this they revile him. Therefore, a man ought to take firm hold in the worship of God, may He be extolled, and know that only two kinds of people can revile him, a fool or a rational man. Now, if he is a fool, it is not proper to pay attention or to heed the sting of his words. And if he be a rational man, one should know that a man of intelligence will not revile a man in an honest matter, unless he is jealous, because he, himself, does not possess that quality.