תהילים ה:י פירוש: רש״י ורד״ק

For there is no sincerity in his mouth They appear as friends but they are enemies.

For there is nothing straightforward in his mouth: – That is the reason why he says because of my watchful foes, for they are men of such a kind that there is no straightforwardness in the mouth (even) of one of them, but they make themselves appear to be friends.

there is malice in their heart Their thoughts are deceitful.