His Interpretations of the Oracles of the Lord in five books, the prime early authority as to the Gospel of Matthew and Gospel of Mark, is known only through fragments in later writers, chiefly Eusebius of Caesarea in "Ecclesiastical History", the earliest and only history book of the early church.

Eusebius had a bias against Papias on account of the influence which his work had in perpetuating, through Irenaeus and others, belief in a millennial reign of Christ upon earth. He calls him a man of small mental capacity, who took the figurative language of apostolic traditions for literal fact. This may have been so to some degree; but Papias (whose name itself denotes that he was of the native Phrygian stock, and who shared the enthusiastic religious temper characteristic of Phrygia, see Montanism) was nearer in spirit to the actual Christianity of the sub-apostolic age, especially in western Anatolia, than Eusebius realized.

Yet Papias admits in his treatise (Interpretations of the Oracles of the Lord) that he had in no way been a hearer or eye witness of the apostles. He says he gathered material from those who were their followers. He did not suppose written information would help as much as the word of the living.

Papias says he heard things that came from an unwritten tradition, some strange parables and teachings of the savior, and some other more mythical accounts. He also heard stories about Justus, surnamed Barsabas, who drank poison but suffered no harm. And another concerning the resurrection of a corpse from a daughter of Philip the Evangelist (Ecclesiastical History Book 3.34. 377-392)

Papias also believed a strange story as to the swelling of the body of Judas Iscariot. Judas became so big he could not pass where a chariot could easily. He was crushed by a chariot, so that his bowels gushed out.(Papias Fragment 3 1742-1744). If Papias was credulous of such stories, just how credulous was Papias of other claims? That we will never know. We can only guess. Such is the way when examining surviving documents from the ancient past. The "truth" of the material is left up to the reader.(Critically studying the ancient past is not everyone's cup of tea. One must be able to treasure the "unknown" and be able to accept and enjoy the value of uncertainty). Papias was also a pioneer in the habit, later so general, of taking the work of the Six Days (Hexaemeron) and the account of Paradise as referring mystically to Christ and His Church (so says Anastasius of Sinai).

About his date, which is important in connexion with his witness, there is some doubt. Setting aside the discredited tradition that he was martyred along with Polycarp (c. AD 155) we have the witness of Irenaeus that he was "a companion of Polycarp," who was born not later than AD 69. We may waive his other statement that Papias was "a hearer of John," owing to the possibility of a false inference in this case. But the fact that Irenaeus thought of him as Polycarp's contemporary and "a man of the old time," together with the affinity between the religious tendencies described in Papias's Preface (as quoted by Eusebius) and those reflected in the Epistles of Polycarp and Ignatius, all point to his having flourished in the first quarter of the 2nd century. Indeed, Eusebius, who deals with him along with Clement and Ignatius (rather than Polycarp) under the reign of Trajan, and before referring at all to Hadrian's reign, suggests that he wrote about AD 115. It has been usual, however, to assign to his work a date c. 130-140, or even later. No known fact is inconsistent with c. 60-135 as the period of Papias's life. Eusebius (3.36) calls him "bishop" of Hierapolis, but whether with good ground is uncertain.

Parts of Interpretations of the Oracles of the Lord were also preserved in Irenaeus' Against Heresies.