Catholic Answers: The Didache
The Didache (pronounced DID-ah-KAY) may be the earliest surviving Christian work outside the New Testament. It speaks as if apostles are still travelling, and it gives the reader tips on how to tell a true apostle from a false one. (Hint: If he tries to mooch off a local church, he’s a false one.) This points to an early date, perhaps in the mid 1st century.
The document provides a basic instruction on certain aspects of the Christian faith. It includes a treatment of Christian morality (including a condemnation of abortion), information about celebrating the sacraments of baptism and the Eucharist, prayer and fasting, Church leaders, and even a little about the end of the world. –Jimmy Akin
The Lord’s Teaching Through the Twelve Apostles to the Nations.
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