In chapter 14 of the Didache, a work dating to about 100 A.D., we read the following: “On the Lord’s own day gather together and break bread and give thanks, having first confessed your sins so that your sacrifice [i.e. the Eucharist] may be pure. But let no one who has a quarrel with a companion join you until they have been reconciled so that your sacrifice may not be defiled. For this is the sacrifice concerning which the Lord said, ‘In every place and time offer me a pure sacrifice, for I am a great king, says the Lord, and my name is marvelous among the nations.’” (The citation is from Malachi 1:11.)