Unlike the Pharisees and the Essenes, the Sadducees left no writings. Some scholars have thought to discover a Sadducaean tendency in First Maccabees, but it certainly cannot be considered a Sadducaean book. All the texts on the Sadducees at our disposal were written by their opponents or, at the least, by outsiders. They are necessarily selective and tendentious. Our main witness is Flavius Josephus who, being a scion of a high-ranking priestly family, might be expected to be close to the Sadducees or, at the least, to have inside information about them. He says that in his youth he tested the Sadducaean teaching and way of life, but his writings betray no special knowledge of them. He speaks of the Sadducees almost exclusively in connection with the other groups of the Judaism of his time.
The New Testament provides the earliest references to the Sadducees, in the Gospel of Mark. This gospel frequently names them among the opponents of Jesus, but it does not develop a coherent picture of them. For the New Testament, the Sadducees are entirely secondary to the Pharisees, who are represented as the main group of Judaism and the only important opponents of Jesus.
The Rabbinic sources frequently mention the Sadducees. But these texts have to be used with extreme caution: one has to discard those texts in which the term Sadducees replaces an original mín (which had to be removed because of Church censorship); only a few Tannaitic texts remain, and even they are not fully reliable historically; later texts display no specific knowledge of the historical Sadducees and offer clichés without revealing new information that can be trusted.