Only - That is, This is "all" that will occur to you. The only thing which you have to anticipate is, that you will see how God punishes sinners.
With thine eyes shalt thou behold and see the reward of the wicked - Your own eyes shall see it. See the notes at Psalm 37:34. You will see the just punishment of the ungodly, the vicious, the profane, the sensual. You will see what is the proper fruit of their conduct; what is the just expression of the views which God takes of their character. This undoubtedly refers to the general principle that there is a moral government on earth; that vice is often punished as such; that the general course of the divine dealings is such as to show that God is favorable to virtue, and is opposed to vice. The system is not complete here, and there are many things which could not be reconciled with this, if the present world were all, and if there were no future state: but the course of events indicates the general character of the divine administration, and what is the tendency of things. The completion - the actual and perfect adjustment - is reserved for a future state. The facts as they occur on earth prove that there is an attribute of justice in God; the fact that his dealings here are not wholly and fully in accordance with what justice demands, proves that there will be a state where full justice will be done, and where the whole system will be adjusted.

The reward of the wicked - Thou shalt not only be safe thyself, but thou shalt see all thy enemies discomfited and cast down.

Only with thine (f) eyes shalt thou behold and see the reward of the wicked.
(f) The godly will have some experience of God's judgements against the wicked even in this life, but they will see it fully at that day when all things will be revealed.

Only with thine eyes shall thou behold,.... The flying arrow, the walking pestilence, and wasting destruction, and the great devastations made by it:
and see the reward of the wicked; the vengeance of God upon them, and this as a just punishment for their sins; not looking upon it with delight and pleasure, rejoicing in the misery of their fellow creatures, any otherwise than as the glory of divine justice is displayed in it; see Psalm 52:6, the pestilence is always threatened, and it always comes, as a Judgment upon a wicked generation of men; and so it is ever to be considered, and is considered by good men, Leviticus 26:5.