Shared ground
These lines present a sharp contrast: the speaker is pursuing what is good, yet his opponents are strong, active, and increasingly numerous. The basic claim is not only that he has enemies, but that their hostility is unfair (“without reason”) and morally inverted (returning evil for his good).
The passage also assumes that doing good does not automatically produce social approval. In the speaker’s experience, goodness can become the very reason others target him.
Where interpretation differs
What “without reason” means. Some read it as “there was no trigger at all.” Others read it as “there is no valid moral justification,” even if the opponents can point to some pretext.
What “because I follow what is good” means. Some take this as the speaker’s account of the opponents’ true motive: they oppose him precisely because he pursues what is right. Others hear it as describing how the conflict is framed publicly: his pursuit of good is the stated issue, but the opponents may be twisting it into an accusation.
Why the disagreement exists
The key phrases (“without reason,” “because”) can describe either objective reality (no real cause; true motive) or the ethical evaluation of the situation (no just cause; conflict framed around his “good”). The Hebrew wording is brief, so readers must infer how much is inner motive, how much is public accusation, and how absolute “without reason” is.
What this passage clearly contributes
Textually, it contributes several linked claims: opponents can be many and energetic; hatred can be unjust; and wrongdoing can include repaying good with evil. The speaker also identifies a moral direction for himself—he is “following what is good” (using the language of good/rightness, good). The verses intensify the psalm’s theme of social isolation and unfair hostility right before the renewed plea for help in Psalm 38:21–22.