Therefore, brethren, stand fast; and hold the traditions which you have learned, whether by word, or by our epistle.
~2 Thessalonians 2:14
The earliest Church Fathers, (within two generations of the Twelve Apostles of Christ) are usually called the Apostolic Fathers since tradition describes them as having been taught by the twelve. Important Apostolic Fathers include Clement of Rome, Ignatius of Antioch and Polycarp of Smyrna. In addition, the Didache and Shepherd of Hermas are usually placed among the writings of the Apostolic Fathers although their authors are unknown; like the works of Clement, Ignatius and Polycarp, they were first written in Koine Greek.
~Wikipedia.org
