Passage
Mark the perfect, and behold the upright, for the end of [that] man is peace;
Mark the perfect, and behold the upright, for the end of [that] man is peace;
Psalms 37:35 I have seen the wicked in great power, and spreading like a green tree in its native soil:
Psalms 37:36 but he passed away, and behold, he was not; and I sought him, but he was not found.
Psalms 37:37 Mark the perfect, and behold the upright, for the end of [that] man is peace;
Psalms 37:38 but the transgressors shall be destroyed together; the future of the wicked shall be cut off.
Psalms 37:39 But the salvation of the righteous is of Jehovah: he is their strength in the time of trouble.
The verse centers on "mark", "perfect", "behold", "upright", and "peace". It is saying that the verse draws attention to "mark" and "perfect", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 36's "but he passed away and behold he..." into verse 38's "but the transgressors shall be destroyed together...", so "mark" and "perfect" belong inside that flow. In Psalms context, the local focus is worship, trust, the LORD's kingship, and covenant mercy.
A plain takeaway is to answer the verse's own emphasis on "mark" and "perfect" with trust shaped by these words, not by a vague optimism outside the passage.