Verse 1:
The man is ever blessedVerse 4:
Who shuns the sinners' ways,
Among their counsels never stands,
Nor takes the scorners' place,
Not so the wicked race,These are the only two verses (of six) where the two rhyming lines are both about the wicked (either directly or, in the case of the first verse, how the righteous man avoids the ways of the wicked). Significantly, these lines have imperfect rhymes. "Ways" doesn't really rhyme with "place," and while "find" and "wind" look like they would rhyme, they don't.
They no such blessings find;
Their hopes shall flee like empty chaff
Before the driving wind.
The rhymes here indicate the imperfection of the wicked. The righteous have perfection through their faith in Christ's death for their sins, and - accordingly - the rhymes in the stanzas that describe them are perfect rhymes (in verse 2 "delight" rhymes with "night," and in verse 3 "root" rhymes with "fruit"). But the wicked are left with their imperfection.