Didache: the Doctrine of the Twelve Apostles.
The Didache or The Teaching of the Twelve Apostles is a short treatise which was accounted by some of the Fathers as next to Holy Scripture, dated by most modern scholars to the first century.. It was rediscovered in 1873 by Bryennios, Greek Orthodox metropolitan of Nicomedia. The text, parts of which constitute the oldest extant written catechism, has three main sections dealing with Christian ethics, rituals such as baptism and Eucharist, and Church organization: the first part is the “Two Ways”, the Way of Life and the Way of Death; the second part is a ritual dealing with baptism, fasting, and Holy Communion; the third speaks of the ministry.
The Didache is considered the first example of the genre of the Church Orders. More than any other Christian scripture, the Didache reveals how Jewish Christians saw themselves and adapted their practice for gentile Christians. The Didache is similar in several ways to the Gospel of Matthew, perhaps because both texts originated in similar communities. The opening chapters are likely derived from an earlier Jewish source, and they also appear in other early Christian texts.
The work was considered by some Church Fathers as part of the New Testament, while being rejected as spurious or non-canonical by others, and eventually was not accepted into the New Testament canon. The Ethiopian Orthodox Church”broader canon” includes the Didascalia, a work which draws on the Didache.