John Calvin Commentary Psalms 101:3

"I will set no base thing before mine eyes: I hate the work of them that turn aside; It shall not cleave unto me." — Psalms 101:3 (ASV)

I will not set a wicked thing before my eyes. After having declared that in leading a private life, he would practice virtue and righteousness, just as it is fitting for good rulers to begin with this, he now adds that in carrying out his duties as a ruler, he will be the enemy of all injustice and wickedness.

To set a wicked thing before one’s eyes is equivalent to intending to do something wicked. He therefore declares that he will turn away from all wickedness. It is certain that no one can be a just and impartial punisher of wrongdoing unless he abhors it with all his heart.

From this it follows that rulers, to perform their duty, must keep themselves entirely free from consenting to any wickedness. Some connect to the first sentence the word עשוה, asoh, which we translate work, and supply the letter ל, lamed; as if it meant: "I will not set before my eyes any wickedness to do it," or, "nothing wicked will be acceptable to me to execute it." But the other meaning is more probable: that David, after having declared that he will not tolerate any iniquity before his eyes, immediately adds to confirm this, that he will be an enemy to all injustice. If the last clause is referred to the people who turn aside, there is a change of number. It may, however, be explained as referring to the work itself, implying that he would never have any part in wicked departures from the path of righteousness.