John Gill Commentary Psalms 74:21

"Oh let not the oppressed return ashamed: Let the poor and needy praise thy name." — Psalms 74:21 (ASV)

O let not the oppressed return ashamed From the throne of grace, not having an answer of their prayer, but still continuing under the oppressions of their enemies:

let the poor and needy praise your name; let them have occasion for it, by the destruction of their enemies, and their deliverance from them, as they will have before long; see (Revelation 19:1Revelation 19:2) .