Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[293] Now there was one Jonathan, a very great friend of Hyrcanus's, but of the sect of the Sadducees, whose notions are quite contrary to those of the Pharisees. He told Hyrcanus that Eleazar had cast such a reproach upon him, according to the common sentiments of all the Pharisees, and that this would be made manifest if he would but ask them the question, What punishment they thought this man deserved? for that he might depend upon it, that the reproach was not laid on him with their approbation, if they were for punishing him as his crime deserved. So the Pharisees made answer, that he deserved stripes and bonds, but that it did not seem right to punish reproaches with death. And indeed the Pharisees, even upon other occasions, are not apt to be severe in punishments. At this gentle sentence, Hyrcanus was very angry, and thought that this man reproached him by their approbation. It was this Jonathan who chiefly irritated him, and influenced him so far, that he made him leave the party of the Pharisees, and abolish the decrees they had imposed on the people, and to punish those that observed them. From this source arose that hatred which he and his sons met with from the multitude: but of these matters we shall speak hereafter. What I would now explain is this, that the Pharisees have delivered to the people a great many observances by succession from their fathers, which are not written in the laws of Moses; and for that reason it is that the Sadducees reject them, and say that we are to esteem those observances to be obligatory which are in the written word, but are not to observe what are derived from the tradition of our forefathers. And concerning these things it is that great disputes and differences have arisen among them, while the Sadducees are able to persuade none but the rich, and have not the populace obsequious to them, but the Pharisees have the multitude on their side. But about these two sects, and that of the Essens, I have treated accurately in the second book of Jewish affairs.