Psalm 53:1-6

⁶ Oh, that the salvation of Israel would come out of Zion!
When God brings back the captivity of His people,
Let Jacob rejoice and Israel be glad.

This psalm represents an iteration, with minor variations, of Psalm 14, the reason being to emphasize the unchanging anatomy of human folly (viz., it’s essence and pervasiveness). The concise instruction “according to Mahalat” most likely designating the melody according to which the psalm was to be sung, though the meaning of the term “Mahalat” is uncertain (suggestions include “sickness,” “entreaty,” or “pardon”). — Wechsler, pages 150-151.

Quoted in Romans 3:10-12

fool (v.1) = one with a withered intellect — In Scripture, it refers to the wicked who aggressively and intentionally boast of their independence from God and His commandments, who deny His existence or deny the existence of divine justice.

abominable (v.1) = abhorred, detested

looks down (v.2) — referring to God’s assessment of the heart of men

That this passage is applied to Jews as well as Gentiles is shown by the use of the same phrases in other passages applying directly to Israel. For example, “they have become corrupt” (Deuteronomy 31:29); “they have turned aside” (Isaiah 1:23).

The main variation between this psalm and Psalm 14 is centered in verse 5, which complements the emphasis on God’s sympathy and proximity to the righteous in the structurally parallel passage in Psalm 14:5-6 by here emphasizing His judgment and rejection of those (i.e., the Gentile nations, who in the Old Testament are generally identified with the enemies of the True God) who encamped against David’s people. — Wechsler, page 151.

The other difference between this psalm and Psalm 14 is the use here of Elohim in all seven mentions of God while the earlier psalm used Jehovah four times.

Here’s Williams’ take:

In Psalm 14, the attention of the reader is directed to the suffering of Messiah and His servants. It is for private use. Its purpose is to sustain Israel’s faith in her future affliction of which that under Pharaoh was a fore-picture. In Psalm 53, “instruction” is given respecting the judgment of the oppressor and the deliverance of the oppressed. It is for public use. The psalm instructs the Fool and his followers respecting the judgment that must overtake them if they do not confess their abominable iniquities and seek forgiveness for them. Psalm 14:6 pictures the Fool and his followers putting the afflicted of Israel to shame; Psalm 53:5 views the Messiah putting the Fool and his followers to shame. But in both psalms, as also in Romans 1 and 2, God’s moral judgment of man, as man, whether he be a Jew or a Gentile, is declared to be the same — all are corrupt. — Williams, pages 341-342.