Charles Ellicott Commentary Proverbs 21:6

"The getting of treasures by a lying tongue Is a vapor driven to and fro by them that seek death." — Proverbs 21:6 (ASV)

It is a vanity tossed to and fro of those who seek death. —Rather, is (as) the driven (fleeting) breath of those who are seeking death. They are seeking in reality not riches, but death, and these riches will vanish like their own breath. (Psalms 68:2).