This is a psalm in praise of YHWH. The principle idea of it is that once a man has put his trust in YHWH and taken Him as his refuge he can stand firm against all opposition, whatever the danger, because YHWH is with him. For YHWH looks down and sees all, and brings about His righteous will. And it stresses that such a man will not stoop to the evil behaviour of the unrighteous in retaliation, for to do so would shake the very foundations of God's Law. To behave in such a way would be to make him evil too. And then what would the righteous do? To whom would they be able to turn? It is a firm statement that if men behave unrighteously towards us it does not justify our behaving in the same way towards them.