Charles Ellicott Commentary Proverbs 26:23

"Fervent lips and a wicked heart Are [like] an earthen vessel overlaid with silver dross." — Proverbs 26:23 (ASV)

Burning lips— that is, burning with love, while there is an evil heart within.

A potsherd covered with silver dross.— Pottery glazed with dross of silver, a well-known method of ornamentation. For similar proverbs, compare Matthew 23:27 and Luke 11:39.