to keep our tongue from evil
Who is the man who desires life, and loves many days; that he may see good? Keep your tongue from evil, And your lips from speaking deceit. (Ps 34:12-13)
The devil is the father of all lies. A person who speak many lies, have his father the devil. However, God loves truth and the bearers of truth. If we are God's children we will be able to discern the truth from deceit.