King James Version (KJV)
Their tongue {is as} an arrow shot out; it speaketh deceit: {one} speaketh peaceably to his neighbour with his mouth, but in heart he layeth his wait. {in heart: Heb. in the midst of him} {his wait: or, wait for him}
Modern English
Their tongue is a deadly arrow. It speaks deceit. One speaks peaceably to his neighbor with his mouth, but in his heart, he waits to ambush him.
Hebrew
הַעַל־אֵ֥לֶּה לֹֽא־אֶפְקָד־בָּ֖ם נְאֻם־יְהוָ֑ה אִ֚ם בְּג֣וֹי אֲשֶׁר־כָּזֶ֔ה לֹ֥א תִתְנַקֵּ֖ם נַפְשִֽׁי׃
haʿal-ʾeleh loʾ-ʾepqad-bam nʾum-yhvah ʾim bgvoy ʾasher-kazeh loʾ titnaqem napshiy