When the Buddha said: "Censured or praised by the wise?" In a few suttas, when talking about right actions, who exactly were those wise?
According to the commentaries:
buddhādīhi viññūhi pasatthattā viññuppasatthāni
"The state of being praised by the wise, starting with the Buddha, [makes them] praised-by-the-wise."
In general, the word viññū just means someone with wisdom. The idea here is that the wiser the person is, the more likely they are to praise that which is worthy of praise and censure that which is worthy of censure.
That phrase is found in, for example, the Kalama Sutta: To the Kalamas.
The introduction, to that sutta, talks about having wise friends:
[...] Instead, any view or belief must be tested by the results it yields when put into practice; and — to guard against the possibility of any bias or limitations in one's understanding of those results — they must further be checked against the experience of people who are wise. The ability to question and test one's beliefs in an appropriate way is called appropriate attention. The ability to recognize and choose wise people as mentors is called having admirable friends. According to Iti 16-17, these are, respectively, the most important internal and external factors for attaining the goal of the practice. For further thoughts on how to test a belief in practice, see MN 61, MN 95, AN 7.79, and AN 8.53. For thoughts on how to judge whether another person is wise, see MN 110, AN 4.192, and AN 8.54.
An example of that phrase being used, in the sutta, is,
When you know for yourselves that, 'These qualities are unskillful; these qualities are blameworthy; these qualities are criticized by the wise; these qualities, when adopted & carried out, lead to harm & to suffering' — then you should abandon them.
So perhaps we should see the phrase in three or four ways:
As an abstraction -- "Praised by the wise" is synonym of "wise", "criticized by the wise" is a synonym of "unwise" (e.g. "these properties are unskillful, blameworthy, unwise").
I also read it as being, possibly, a rhetorical device (e.g. "the wise criticize it, and you want to be with or like the wise, so you should criticize it too").
As companions -- "The wise" are ... well I think you're supposed to know who the wise are, within your community. If you don't know, maybe your parents or teacher or best friend can tell you who they are, or the introduction suggests how to judge whether a person is wise.
As self -- "We" are supposed to be wise. The sutta says, "When you know for yourselves that..."
As Buddha -- In context, "the wise" are (by definition) whoever agrees with (and practices) what the Buddha is saying.