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

[103] About this time it was that the people of Damascus, out of their hatred to Ptolemy, the son of Menhens, invited Aretas [to take the government], and made him king of Celesyria. This man also made an expedition against Judea, and beat Alexander in battle; but afterwards retired by mutual agreement. But Alexander, when he had taken Pella, marched to Gerasa again, out of the covetous desire he had of Theodorus's possessions; and when he had built a triple wall about the garrison, he took the place by force. He also demolished Golan, and Seleucia, and what was called the Valley of Antiochus; besides which, he took the strong fortress of Gamala, and stripped Demetrius, who was governor therein, of what he had, on account of the many crimes laid to his charge, and then returned into Judea, after he had been three whole years in this expedition. And now he was kindly received of the nation, because of the good success he had. So when he was at rest from war, he fell into a distemper; for he was afflicted with a quartan ague, and supposed that, by exercising himself again in martial affairs, he should get rid of this distemper; but by making such expeditions at unseasonable times, and forcing his body to undergo greater hardships than it was able to bear, he brought himself to his end. He died, therefore, in the midst of his troubles, after he had reigned seven and twenty years.