The Didache is also called the "Teaching of the Twelve Apostles."  It was possibly written around 65 - 80 A.D. and is supposed to be what the twelve apostles taught to the Gentiles concerning life and death, church order, fasting, baptism, prayer, etc.  There is debate as to its authenticity.  The work is cited by Eusebius who lived from 260 - 341 and Athanasius 293-373.  It seems to be referenced by Origen who lived from 185-254.  In the Didache, 16:2-3 is quoted in the Epistle of Barnabas in 4:9, or vice versa. The Epistle of Barnabas was written in 130-131 A.D.  The Didache is not inspired but is valuable as an early church document.