The Didache is the oldest book/catechism/constitution, etc. of information, that we have. It has been dated as around 50 A.D.. It contains the teachings of the twelve apostles. It was found by the Metropolitan Philotheos Bryennios in a Greek manuscript in Constantinople. Although, it has been moved to a safer place. Think of it. This is older than the Gospel of John and some of the synoptic letters.
Inside is a manual of instruction for the community on how to prepare catechumen for baptism. Catechumen is Greek for people taking instructions in the faith. It also gives the form of the rite to be used and other practical advice.
IOW, it is a manual that outlines teachings, rites, and instructions. Here are the instructions for the Rite of Reconciliation (Confession).
In the church you shall acknowledge your transgressions, and you shall not come near for your prayer with an evil conscience. This is the way of life. . . . But every Lord’s day gather yourselves together and break bread and give thanksgiving after having confessed your transgressions, that your sacrifice may be pure. – Didache 4, 14 (50 A.D).




