A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown [1882] at sacred-texts.com
Sinners are termed "fools," because they think and act contrary to right reason (Gen 34:7; Jos 7:15; Psa 39:8; Psa 74:18, Psa 74:22).
in his heart--to himself (Gen 6:12).
looked--in earnest enquiry.
understand--as opposed to "fool" [Psa 14:1].
filthy--literally, "spoiled," or, "soured," "corrupted" (Job 15:16; Rom 3:12).
Their conduct evinces indifference rather than ignorance of God; for when He appears in judgment, they are stricken with great fear.
who eat up my people--to express their beastly fury (Pro 30:14; Hab 3:14). To "call on the Lord" is to worship Him.
captivity--denotes any great evil.
Zion--God's abode, from which He revealed His purposes of mercy, as He now does by the Church (compare Psa 3:4; Psa 20:2), and which He rules and in which He does all other things for the good of His people (Eph 1:22).