In the foregoing verse the thoughts of the wicked and righteous were compared; here their words, and those are as the abundance of the heart is. 1. Wicked people speak mischief to their neighbours; and wicked indeed those are whose words are to lie in wait for blood; their tongues are swords to those that stand in their way, to good men whom they hate and persecute.
See an instance, Luke 20:20-21. 2. Good men speak help to their neighbours: The mouth of the upright is ready to be opened in the cause of those that are oppressed (Proverbs 31:8), to plead for them, to witness for them, and so to deliver them, particularly those whom the wicked lie in wait for.
A man may sometimes do a very good work with one good word.