His mouth is full of cursing. (On the prevalence of this evil habit among the powerful in David's time, see Psalms 59:12; Psalms 109:17, Psalms 109:18; 2 Samuel 16:5.) And deceit and fraud; or, guile and extortion (Kay); comp.
Psalms 36:3; Psalms 55:11. Under his tongue is mischief and vanity; rather, as in the margin, mischief and iniquity. These are stored "under his tongue," ready for utterance whenever he finds a fit occasion.