Assemble on the Lord’s day, and break bread and offer the Eucharist; but first make confession of your faults, so that your sacrifice may be pure. Anyone who has a difference with his fellow is not to take part until he has been reconciled, so as to avoid profaning your sacrifice [Mt 5:23–24]. For this is the offering of which the Lord said, “Everywhere and always bring me a sacrifice that is undefiled, for I am a great king, says the Lord, and my name is the wonder of nations” [Mal 1:11, 14].

Didache