paradidonai = tradere, traditio
unwritten but unaltered. In such circles it would be entirely natural to treat the earliest account of Jesus' deeds and words in just this way. It is to this practice that Paul unmistakably refers, quoting from the Christian tradition our oldest account of the institution of the Lord's Supper, I Cor. 11:24, 25. It will be noted that he speaks of having previously passed this account on to the Corinthians. He speaks in a similar way in I Cor. 15:3-7 of the resurrection accounts which he had communicated to them: "I passed onto you as of first importance, the account I had received."
Acts similarly speaks of "remembering the words of the Lord Jesus," 20:35, and quotes words of Jesus that have never been found in any written gospel. Clement of Rome, in writing to the Corinthians about A.D.95, in two places—13:1 and 46:7, 8—quotes sayings of Jesus not quite like any in our gospels, admonishing his readers in both passages to "remember the words of the Lord Jesus." Polycarp of Smyrna in his letter to the Philippians, about A.D. 107-17, does the same, introducing the quotation with the words, "Remembering what the Lord said," Phil. 2:3. It seems clear that all four are quoting an Oral Gospel.
This is internal evidence. Is there any external evidence,
 This attitude is clearly reflected in the story that Gamaliel the First, about A.D. 50, seeing a written copy of an Aramaic translation of Job, immediately had it destroyed. The Targum was not to be written but remembered; cf. Meyer Waxman, History of Jewish Literature (New York, 1930), II, p. 113.
 All these writers quote written documents in quite another way: I Cor 7:1; Gal. 3:13; Acts 1:20; I Clem. 47:1, 2; Pol. Phil. 3:2.
any possible reference to such a work, in out earliest Christian writings? It was, of course, the Jewish practice to preserve in oral form the sayings of the great rabbis, as the Pirqe Aboth ("The Sayings of the Fathers") shows. Conditions among the earliest Christians, who thought of Jesus as among other things a "rabbi"—Mark 9:5; 10:51; 11:21; 14:45, etc.—or a "teacher" (twelve times in Mark), favor such a way of preserving his teaching; it would, in fact, have been inevitable; and subsequent quotations seem to show its use, as we have seen. But is there anything that looks like an actual ancient mention of it by name?
In the early years of the second century there lived in Hierapolis, in Asia, a Christian bishop named Papias, who made it his business to interview any Christian of the previous generation who came near and to record these memorabilia in a book, which he called Interpretations of the Lord's Sayings. Though the book existed in convent libraries in Europe until the thirteenth and fourteenth centuries,  it seems now to have disappeared, except for a few fragments of it quoted by ancient or medieval writers. One of these was Eusebius, who in his famous Church History, finished in A.D. 326, quoted this sentence from Papias:
"So then Matthew composed the Sayings in the Aramaic language and each one translated them as [best] he could."
 A. Harnack, Geschichte der altchristlichen Litteratur: Die Ueberlieferung, und der Bestand (Leipzig, 1893), p. 69.
 Church History iii. 39, 15.
Edgar J. Goodspeed, An Introduction to the New Testament, p. 126-128