גִרְרִין דְגִבָּרָא שְׁנוּנִין הֵיךְ בַּרְקִין מִלְעֵיל עִם גוּמְרֵי רִתְמִין דְדָלְקִין בִּגְהִנָם מִלְרַע.
1. sharp arrows | חִצֵּי גִבּוֹר שְׁנוּנִים – See Rashi and others that the images in this verse are metaphors for the deceitful tongue. It can injure from afar like an arrow and it can cause harm long after one thinks that ill will has dissipated, like a coal which still burns inside, even if it is cool to the touch [see the next footnote]. Cf. Hoil Moshe that this verse is the answer to the question posed in the previous one; the psalmist says that the deceiver will be punished with burning arrows.
2. broom-wood | רְתָמִים – The "רתם" has been identified with the broom tree. Coals made of this tree are known to retain their heat for an extremely long time and are deceptively hot; though the outside of the coal might be cool, the inside continues to burn. This is an apt metaphor for a deceitful person; he might look harmless but he is full of malice, and the effects of his slanderous speech are long-lasting. [For an image of the broom tree, see Olam HaMikra.]