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

[137] However, when Caesar, after some time, had finished that war, and was sailed away for Syria, he honored Antipater greatly, and confirmed Hyrcanus in the high priesthood; and bestowed on Antipater the privilege of a citizen of Rome, and a freedom from taxes every where; and it is reported by many, that Hyrcanus went along with Antipater in this expedition, and came himself into Egypt. And Strabo of Cappadocia bears witness to this, when he says thus, in the name of Aslnius: "After Mithridates had invaded Egypt, and with him Hyrcanus the high priest of the Jews." Nay, the same Strabo says thus again, in another place, in the name of Hypsicrates, that "Mithridates at first went out alone; but that Antipater, who had the care of the Jewish affairs, was called by him to Askelon, and that he had gotten ready three thousand soldiers to go along with him, and encouraged other governors of the country to go along with him also; and that Hyrcanus the high priest was also present in this expedition." This is what Strabo says.