How much trouble he avoids who does not look to see what his neighbor says or does or thinks, but only to what he does himself, that it may be just and pure.

[Ὅσην εὐσχολίαν κερδαίνει ὁ μὴ βλέπων τί ὁ πλησίον εἶπεν ἢ ἔπραξεν ἢ διενοήθη, ἀλλὰ μόνον τί αὐτὸς ποιεῖ, ἵνα αὐτὸ τοῦτο δίκαιον ᾖ καὶ ὅσιον ἢ † κατὰ τὸν ἀγαθὸν.]

Marcus Aurelius (AD 121-180) Roman emperor (161-180), Stoic philosopher

Meditations [To Himself; Τὰ εἰς ἑαυτόν], Book 4, ch. 18 (4.18) (AD 161-180) [tr. Long (1862)]
    (Source)

Original Greek. Alternate translations:

How much time and leisure doth he gain, who is not curious to know what his neighbour hath said, or hath done, or hath attempted, but only what he doth himself, that it may be just and holy?
[tr. Casaubon (1634), #15]

What a great deal of Time and Ease that Man gains who is not troubled with the Spirit of Curiosity: Who lets his Neighbor's Thoughts and Behavior alone, confines his Inspections to himself' And takes care of the Points of Honesty and Conscience.
[tr. Collier (1701)]

What agreeable leisure does he procure to himself, who takes no no¬ tice what others say, do, or intend; but attends to this only, that his own actions be just and holy?
[tr. Hutcheson/Moor (1742)]

How much time and leisure does that man gain, who is not curious to enquire what his neighbours say, or do, or think, but confines his whole attention to his own conduct, and is only solicitous to preserve that just and irreproachable.
[tr. Graves (1792)]

What a great deal of time and ease that man gains who lets his neighbor's words, thoughts, and behavior alone, confines his inspections to himself, and takes care that his own actions are honest and righteous.
[tr. Collier/Zimmern (1887)]

How much time he gains who does not look to see what his neighbor says or does or thinks, but only at what he does himself, to make it just and holy.
[tr. Morgan, in Bartlett's Familiar Quotations (1894)]

How much valuable time may be gained by not looking at what some neighbor says or does or thinks, but only taking care that our own acts are just and holy.
[tr. Rendall (1898 ed.)]

How much he gains in leisure who looks not to what his neighbours say, or do, or intend; but considers only how his own actions may be just and holy.
[tr. Hutcheson/Chrystal (1902)]

What richness of leisure does he gain who has no eye for his neighbour's words or deeds or thoughts, but only for his own doings, that they be just and righteous!
[tr. Haines (Loeb) (1916)]

How great a rest from labour he gains who does not look to what his neighbour says or does or thinks, but only to what he himself is doing, in order that exactly this may be just and holy, or in accord with a good man's conduct.
[tr. Farquharson (1944); he notes "The text is faulty and the sense obscure."]

He who ignores what his neighbour is saying or doing or thinking, and cares only that his own actions should be just and godly, is greatly the gainer in time and ease.
[tr. Staniforth (1964)]

What ease of mind he gains who casts no eye on what his neighbour says or does or thinks, but looks only to what he himself is doing, to ensure that his own action may be just, and holy, and good in every regard.
[tr. Hard (1997 ed.)]

The tranquility that comes when you stop caring what they say. Or think, or do. Only what you do. (Is this fair? Is this the right thing to do?)
[tr. Hays (2003)]

What ease of mind you gain from not looking at what your neighbour has said or done or thought, but only at your own actions, to make them just, reverential, imbued with good!
[tr. Hammond (2006)]

What an abundance of leisure the person gains who is not looking over at what his neighbor is saying, doing, or thinking, but only at what he himself is doing, in order that he does what is just and respectful of the gods.
[tr. Needleman/Piazza (2008)]

What ease of mind a person gains if he casts no eye on what his neighbour has said, done, or thought, but looks only to what he himself is doing, to ensure that his own action may be just, and holy, and good in every respect.
[tr. Hard (2011 ed.)]

What ease of mind a person gains when he keeps his eye not on what his neighbor has said or done or thought but only on what he himself does, to ensure that it is just or holy or matches what a good person does.
[tr. Gill (2013)]