Albert Barnes 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 – Ashamed by being disappointed, as if they had trusted in what had no claims to confidence. Compare the notes at Job 6:20.

The word rendered “oppressed,” means “trodden down, crushed, broken, afflicted.” It refers to the people as attacked by foreign armies or as crushed by those who had gained power over them.

The word “return” refers to their coming back from God – from the throne of mercy. Let them not come back from You with no assurance of Your favor; with no evidence that their prayers have been heard. Let them not return subject to the reproach that they had appealed to You in vain.

Let the poor and needy praise thy name – The people who are oppressed and helpless. Let them have occasion to praise You because their prayer has been heard and because You save them.