The earliest written reference to the Eucharist (Lord’s Supper/Communion) is 1 Corinthians 11:23–26, written by St. Paul around A.D. 55.

Paul’s description in 1 Corinthians 11 is the earliest written witness to Christians “eating the bread and drinking the cup of the Lord.”  He explicitly links this practice to Jesus’ actions at the Last Supper and treats it as an already-established ritual in the Corinthian church.

This predates the earliest Gospel by at least a decade and is the oldest surviving Christian text describing the rite.  However, scholars do not believe that the gospel writers used Paul as a source for their unique Eucharist accounts, which indicates that practice of the rite was widespread in the Eastern Mediterranean in the first century.

Paul also says he is passing on a tradition he himself received, implying the Eucharist was practiced orally even earlier than his letter.

The earliest known manuscript source for 1 Corinthians is Papyrus 46 (𝔓46) — one of the famous Chester Beatty Papyri — and it is one of the oldest surviving New Testament manuscripts of any kind.

Most scholars date 𝔓46 to around 175–225 A.D., though a minority have argued for an even earlier date.  Even using the conservative date, 𝔓46 is roughly 150 years earlier than the great parchment codices (Vaticanus, Sinaiticus).

Beatty Papyrus 𝔓46, the earliest extant manuscript containing 1 Cor 11:18-25 (175–225 A.D.)

Detailed Illustration of the earliest account of the Eucharist (Greek and English)