Didache (1st Century) 4:14:
At the church meeting you must confess your sins
Didache (1st Century) 14:1-3:
On every Lord's Day—his special day—come together and break bread and give thanks, first confessing your sins so that your sacrifice may be pure. Anyone at variance with his neighbor must not join you, until they are reconciled, lest your sacrifice be defiled. For it was of this sacrifice that the Lord said, "Always and everywhere offer me a pure sacrifice; for I am a great King, says the Lord, and my name is marveled at by the nations."
Epistle of Barnabas (1st Century) Chapter 19:
Thou shalt confess thy sins.
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Find more of what the early Christians thought on my Christian History page!