Jeremiah 5:2 - Joseph Benson’s Commentary on the Old and New Testaments

And though they say, The Lord liveth, &c. Though, when they swear, they use the common form of an oath, and say, The Lord liveth, or, as the Lord liveth, or, by the living God. Surely, or rather, nevertheless, they swear falsely That is, either, 1st, They are not sincere in the profession they make of respect to God, but are false to him; they honour him with their lips, but their hearts are far from him, nor have they any proper conviction or sense that he lives and sees them, Genesis 16:13-14. Or, 2d, Though they appeal to God only, they make no conscience of calling him to witness a lie: though they do not swear by idols, they forswear themselves, which is no less an affront to Jehovah, as the God of truth, than the other is to him, as the only true God.