Psalms 15:4

In whose eyes a vile person is contemned - That is, who does not show respect to a man of base or bad character on account of his wealth, his position, or his rank in life. He estimates character as it is in itself, and not as derived from rank, relationship, or station. While, as stated in the previous verse, he is not disposed to take up a false or evil report against another, he is at the same time disposed to do justice to all, and does not honor those who do not deserve to be honored, or apologise for base conduct because it is committed by one of exalted station or rank. Loving virtue and piety for their own sake, he hates all that is opposite; and where conduct deserves reprobation, no matter where found, he does not hesitate to avow his conviction in regard to it. The sentiment here is substantially the same as in Psalms 1:1. See the notes at that verse.

But he honoreth them that fear the Lord - No matter in what rank or condition of life they may be found. Where there is true piety he honors it. He is willing to be known as one that honors it, and is willing to bear all the reproach that may be connected with such a deeply cherished respect, and with such an avowal. Compare Psalms 1:1.

He that sweareth to his own hurt, and changeth not - Who has made a promise, or entered into a contract, that is likely to turn out contrary to his expectations, to his own disadvantage; but who still adheres to his engagement. If the thing itself is wrong; if he has made a promise, or pledged himself to do a wicked thing, he cannot be under obligation to execute it; he should at once abandon it (compare the notes at Matthew 14:9); but he is not at liberty to violate an agreement simply because it will be a loss to him, or because he ascertains that it will not be, as he supposed, to his advantage. The principles here laid down will extend to all contracts or agreements, pecuniary or otherwise, and should be a general principle regulating all our transactions with our fellow-men. The only limitation in the rule is that above stated, when the promise or the contract would involve that which is morally wrong.