רַגְלֵ֤י חֲסִידָו֙ יִשְׁמֹ֔ר וּרְשָׁעִ֖ים בַּחֹ֣שֶׁךְ יִדָּ֑מּוּ כִּי־לֹ֥א בְכֹ֖חַ יִגְבַּר־אִֽישׁ׃
[God] guards the steps of the faithful,
But the wicked perish in darkness—
For none shall prevail by strength.
(The above rendering comes from the RJPS translation, an adaptation of the NJPS translation. Before accounting for this rendering, I will analyze the plain sense of the Hebrew term containing אִישׁ.)
Prototypically, אִישׁ is used in sketching a situation schematically. Here, it is employed in a species-generic usage, which is evoked by pragmatic strengthening in the context of a contrast with the Deity.
As for rendering into English, the NJPS ‘For not by strength shall man prevail’ construes אִישׁ appropriately as a species-generic usage. However, given that the generic use of man in English is now passé, that particular meaning is now difficult to convey in a poetic context. An indefinite pronoun comes very close and is optimal. (Hence ‘[no/not] one’ is found in NRSV, NLT, NIV.) The revised rendering preserves the poetic feel. Meanwhile, respecting the fronted adjunct (בְכֹחַ) in the Hebrew warrants putting its equivalent at the clause’s end, where focus resides in English.