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

[7] When Bacchides heard this, and was afraid that Jonathan might be very troublesome to the king and the Macedonians, as Judas had been before him, he sought how he might slay him by treachery. But this intention of his was not unknown to Jonathan, nor to his brother Simon; but when these two were apprized of it, they took all their companions, and presently fled into that wilderness which was nearest to the city; and when they were come to a lake called Asphar, they abode there. But when Bacchides was sensible that they were in a low state, and were in that place, he hasted to fall upon them with all his forces, and pitching his camp beyond Jordan, he recruited his army. But when Jonathan knew that Bacchides Was coming upon him, he sent his brother John, who was also called Gaddis, to the Nabatean Arabs, that he might lodge his baggage with them until the battle with Bacchides should be over, for they were the Jews' friends. And the sons of Ambri laid an ambush for John from the city Medaba, and seized upon him, and upon those that were with him, and plundered all that they had with them. They also slew John, and all his companions. However, they were sufficiently punished for what they now did by John's brethren, as we shall relate presently.