Charles Ellicott Commentary Jeremiah 5:2

"And though they say, As Jehovah liveth; surely they swear falsely." — Jeremiah 5:2 (ASV)

The Lord liveth. — The words imply that a distinction between the binding powers of different oath formulas, like that of the later scribes (Matthew 23:16), was already to some extent prevalent. The guilt of the men of Jerusalem was that they took the most solemn formula of all, “Jehovah liveth,” and yet were guilty of perjury. In Jeremiah 5:7 we find traces of the practice of swearing by other gods, with which this “oath of Jehovah” is apparently contrasted.

Falsely. — Literally, upon falsehood.