The Hebrew phrase “counsel of wicked people” (בַּעֲצַת רְשָׁעִים baatsat reshaim, v. 1) sounds almost identical to “group of righteous people” (בַּעֲדַת צַדִּיקִים baadat tsaddiqim, v. 5). The first word in each phrase has nearly the same consonants, and the phrases have a nearly identical rhythm — the kind of sound that makes you think you’ve heard the phrase before.
You have. And that’s the point.
Verse 1 says the righteous person does not stand with the wicked. Verse 5 says the wicked will not stand with the righteous. The same motion verb, the same two groups of people — but the logic inverted. The choice the righteous person makes will, in the end, be made for the wicked. The poem says it twice, once from the inside and once from the outside, using sounds so similar you almost don’t notice the reversal.