The Araṇa-Vibhaṅga Sutta (MN 139) has some interesting points to the topic:
“One should not pursue sensual pleasure, which is low, vulgar, coarse, ignoble, and unbeneficial; and one should not pursue self-mortification, which is painful, ignoble, and unbeneficial. The Middle Way discovered by the Tathāgata avoids both extremes; giving vision, giving knowledge, it leads to peace, to direct knowledge, to enlightenment, to Nibbāna. One should know what it is to extol and what it is to disparage, and knowing both, one should neither extol nor disparage but should teach only the Dhamma. One should know how to define pleasure, and knowing that; one should pursue pleasure within oneself. One should not utter covert speech, and one should not utter overt sharp speech~ One should speak unhurriedly, not hurriedly. One should not insist on local language, and one should not override normal usage. This is the summary of the exposition of non-conflict.
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“‘One should know what it is to extol and what it is to disparage, and knowing both, one should neither extol nor disparage but should teach only the Dhamma.’ So it was said. And with reference to what was this said?
“How, bhikkhus, does there come to be extolling and disparaging and failure to teach only the Dhamma? When one says: ‘All those engaged in the pursuit of the enjoyment of one whose pleasure is linked to sensual desires, low … and unbeneficial, are beset by suffering, vexation, despair, and fever, and they have entered upon the wrong way,’ one thus disparages some. When one says: ‘All those disengaged from the pursuit of the enjoyment of one whose pleasure is linked to sensual desires , low … and unbeneficial, are without suffering, vexation, despair, and fever, and they have entered upon the right way,’ one thus extols some.
“When one says: ‘All those engaged in the pursuit of self-mortification, painful, ignoble, and unbeneficial, are beset by suffering, vexation, despair, and fever, and they have entered upon the wrong way,’ one thus disparages some. When one says: ‘All those disengaged from the pursuit of self-mortification, painful, ignoble, and unbeneficial, are without suffering, vexation, despair, and fever, and they have entered upon the right way,’ one thus extols some.
“When one says: ‘All those who have not abandoned the fetter of being are beset by suffering, vexation, despair, and fever, and they have entered upon the wrong way,’ one thus disparages some. When one says: ‘All those who have abandoned the fetter of being are without suffering, vexation, despair, and fever, and they have entered upon the right way,’ one thus extols some. This is how there comes to be extolling and disparaging and failure to teach only the Dhamma.
“And how, bhikkhus, does there come to be neither extolling nor disparaging but teaching only the Dhamma? When one does not say: ‘All those engaged in the pursuit of the enjoyment of one whose pleasure is linked to sensual desires … have entered upon the wrong way,’ but says instead: ‘The pursuit is a state beset by suffering, vexation, despair, and fever, and it is the wrong way,’ then one teaches only the Dhamma. When one does not say: I All those disengaged from the pursuit of the enjoyment of one whose pleasure is linked to sensual desires … have entered upon the right way,’ but says instead: ‘The disengagement is a state without suffering, vexation, despair, and fever, and it is the right way,’ then one teaches only the Dhamma.
“When one does not say: ‘All those engaged in the pursuit of self-mortification … have entered upon the wrong way,’ but says instead: ‘The pursuit is a state beset by suffering, vexation, despair, and fever, and it is the wrong way,’ then one teaches only the Dhamma. When one does not say: ‘All those disengaged from the pursuit of self-mortification … have entered upon the right way,’ but says instead: ‘The disengagement is a state without suffering, vexation, despair, and fever, and it is the right way,’ then one teaches only the Dhamma.
“When one does not say: ‘All those who have not abandoned the fetter of being … have entered upon the wrong way,’ but says instead: ‘As long as the fetter of being is unabandoned, being too is unabandoned,’ then one teaches only the Dhamma.
When one does not say: ‘All those who have abandoned the fetter of being … have entered upon the right way,’ but says instead: ‘When the fetter of being is abandoned, being also is abandoned,’ then one teaches only the Dhamma.
“So it was with reference to this that it was said: ‘One should know what it is to extol and what it is to disparage, and knowing both, one should neither extol nor disparage but should teach only the Dhamma.’
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“‘One should not utter covert speech, and one should not utter overt sharp speech.’ So it was said. And with reference to what was this said?
“Here, bhikkhus, when one knows covert speech to be untrue, incorrect, and unbeneficial, one should on no account utter it. When one knows covert speech to be true, correct, and unbeneficial, one should try not to utter it. But when one knows covert speech to be true, correct, and beneficial, one may utter it, knowing the time to do so.
“Here, bhikkhus, when one knows overt sharp speech to be untrue, incorrect, and unbeneficial, one should on no account utter it. When one knows overt sharp speech to be true, correct, and unbeneficial, one should try not to utter it. But when one knows overt sharp speech to be true, correct, and beneficial, one may utter it, knowing the time to do so.
“So it was with reference to this that it was said: ‘One should not utter covert speech, and one should not utter overt sharp speech.’
“‘One should speak unhurriedly, not hurriedly.’ So it was said. And with reference to what was this said?
“Here, bhikkhus, when one speaks hurriedly, one’s body grows tired and one’s mind becomes excited, one’s voice is strained and one’s throat becomes hoarse, and the speech of one who speaks hurriedly is indistinct and hard to understand.
“Here, bhikkhus, when one speaks unhurriedly, one’s body does not grow tired nor does one’s mind become excited, one’s voice is not strained nor does one’s throat become hoarse, and the speech of one who speaks unhurriedly is distinct and easy to understand.
“So it was with reference to this that it was said: ‘One should speak unhurriedly, not hurriedly.’
“‘One should not insist on local language, and one should not override normal usage.’ So it was said. And with reference to what was this said?
“How, bhikkhus, does there come to be insistence on local language and overriding of normal usage? Here, bhikkhus, in different localities they call the same thing a ‘dish’ [pāti], a ‘bowl’ [patta], a ‘vessel’ [vittha], a ‘saucer’ [sarāva], a ‘pan’ [dhāropa], a ‘pot’ [poṇa], a ‘mug’ [hana] or a ‘basin’ [pisīla]. So whatever they call it in such and such a locality, one speaks accordingly, firmly adhering [to that expression] and insisting: ‘Only this is correct; anything else is wrong.’ This is how there comes to be insistence on local language and overriding normal usage.
“And how, bhikkhus, does there come to be non-insistence on local language and non-overriding of normal usage? Here, bhikkhus, in different localities they call the same thing a ‘dish’ … or a ‘basin.’ So whatever they call it in such and such a locality, without adhering [to that expression] one speaks accordingly, thinking: ‘These venerable ones, it seems, are speaking with reference to this.’ This is how there comes to be non-insistence on local language and non-overriding of normal usage.
“So it was with reference to this that it was said: ‘One should not insist on local language, and one should not override normal usage.’
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“Therefore, bhikkhus, you should train yourselves thus: ‘We shall know the state with conflict and we shall know the state without conflict, and knowing these, we shall enter upon the way without conflict.’ Now, bhikkhus, Subhuti is a clansman who has entered upon the way without conflict.”