Watson's Fences for the Tongue
Driving home: God has set two natural fences to keep in the tongue, the teeth and the lips. And this commandment is a third fence set about the tongue that it should not break forth into evil.
Martin quotes Watson, who says God has set two natural fences (teeth and lips) and a third fence (the Ninth Commandment) to keep the tongue from breaking forth into evil, illustrating the divine and natural restraints on speech.
The Hebrew word for false witness is not the same as you have in Exodus 20. In Exodus 20, the word primarily focuses upon bearing false testimony in a legal sense. However, the word used in Deuteronomy means any kind of vain or unfounded witness that we bear concerning another. And I say it's vital at the outset to understand the meaning of this commandment because in the quaint words of Watson, and I quote, God has set two natural fences to keep in the tongue, the teeth and the lips.
11:51 - 12:33 Read in full sermon