Revelation 22:18 and 19 tell us that, since the divine revelation has been completed, no one is allowed to add to it or take away from it. In other words, the Bible itself makes it clear that the entire revelation has been completed and closed, and no one is permitted to claim, as the Mormons do, that additional revelation has been given to them.
The teaching of the New Testament as a whole is called the apostles' teaching (Acts 2:42). The apostles' teaching began with the teaching of the Lord Jesus and continued with Peter, John, Paul, and the other apostles. We praise the Lord that we have in our hand the complete divine revelation.
As we read the Bible, we need to learn the principles of the Bible. Especially we need to keep in mind the basic principle that the divine revelation in the Bible is progressive. If we are clear concerning this, we will realize that the speaking of Job's three friends is a matter not of divine revelation but of human opinion. How, then, can we regard their opinion as divine revelation?
We face a similar situation when we come to the Psalms. I appreciate the comment of John Nelson Darby that the Psalms are the expressions of the psalmists uttered out of their complex sentiments. We should not regard every aspect of the psalmists' sentiments as the divine revelation. It would be very unwise for us to do this. On the one hand, the psalmists received a certain amount of the divine revelation; on the other hand, their receiving of this revelation caused them to have various sentiments, including sentiments related to hating their enemies, to doing good, and to keeping the law.
Many Christians appraise the Psalms very highly and even exalt them. On the contrary, I have been helped by Darby to see that some of the expressions in the Psalms are not the direct expression of the divine revelation but the expression of the complex sentiments of the psalmists. The psalmists who uttered these expressions were pious; they loved God, feared God, and tried their best to please God, trust God, and keep the law. With the exception of trying to keep the law, all these things are good. Trying to keep the law is contrary to one of the principles of the Bible. The law was not given for God's people to keep; rather, the law was given to try them, to prove them, and to convince them that they were unable to keep the law.