James 3:8
7 For every kind of animal, bird, reptile, and sea creature is subdued and has been subdued by humankind. 8 But no human being can subdue the tongue; it is a restless evil, full of deadly poison. 9 With it we bless the Lord and Father, and with it we curse people made in God’s image. 10 From the same mouth come blessing and cursing. These things should not be so, my brothers and sisters.
Didache 2:4
3 You shall not commit perjury; you shall not lie; you shall not speak ill; you shall not bear grudges. 4 You shall not be double-minded or speak with a double-tongue, for to do so leads to death. 5 Your words shall not be false or meaningless but followed by actions. 6 You shall not be greedy or exploitative, nor a hypocrite, nor evil-minded, nor arrogant, you shall not plan evil against your neighbor.
Notes and References
"... Didache 2:4 ... This text seems dualistic at first, however, there is ample precedent in the Old Testament, especially the Wisdom tradition. Thus, Proverbs 21:6 comes quite close to the sense of this text. See also Proverbs 13:14; 14:27; Psalms 18:5; Tobit 14:10; Sirach 28:13-26. James 3:8 also contains the idea that the unruly tongue bears death ..."
Draper, Jonathan Alfred A Commentary on the Didache in the Light of the Dead Sea Scrolls and Related Documents (p. 53) St. John's College, 1983