John Gill Commentary Psalms 50:19

"Thou givest thy mouth to evil, And thy tongue frameth deceit." — Psalms 50:19 (ASV)

Thou givest thy mouth to evil
To speak evil things against Christ, his doctrines, ordinances, ministers and people; and to deliver out evil doctrines, pernicious to the souls of men;

and thy tongue frameth deceit ;
puts and joins together deceitful words in a very artful manner, by which simple and unstable minds are beguiled.