Psaumes 15:4

A base person is despised in his eyes One who is base with his wickedness is despised in the eyes of the righteous man, e.g. Hezekiah, who dragged his father’s remains in disgrace.

he swears to hurt himself.

and does not retract his oath. How much more does he not retract it if it concerns something that is not to his hurt!

Despised is he in his own eyes, rejected: – He recounts further some of his good qualities. For although he walketh perfectly and worketh righteousness and speaketh truth, he does not pride himself upon this, but is despised in his own eyes and rejected, thinking in his heart that he cannot perform one-thousandth part of what it is his duty to do for the honour of his Creator.

But he honoureth them that fear the Lord: – He is despised in his own eyes, but he honoureth them that fear the Lord; for all the good things he has done he counts as nothing compared with what he considers he ought to do, while the good (works) another does he holds to be great things. He feels too that there are others among those who fear the Lord in a superior degree to himself, and that they fear the Name more than he, and so he imputes to them superiority over himself, and honours them. And he makes a further enumeration of his good qualities:

He sweareth to his own hurt: – The interpretation of להרע (to his hurt) is to the hurt of his body in fasting, and in abstinence from pleasures; and so to be in want of clothing even for the sake of righteousness and the mitzvoth.

and changeth not – what he has sworn, although it be to the injury of his person. He will not change, but carry it out as he has promised. And as regards the expression he uses, sweareth, (it is) because when he has spoken a hard thing against himself, he sweareth so that the evil impulse shall not distract him from the performance of it. And so David says (Ps. 119:106): “I have sworn and have confirmed it, that I will observe Thy righteous judgments.”