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

[100] Now when the tribe of Reuben, and that of Gad, and as many of the Manassites as followed them, were passed over the river, they built an altar on the banks of Jordan, as a monument to posterity, and a sign of their relation to those that should inhabit on the other side. But when those on the other side heard that those who had been dismissed had built an altar, but did not hear with what intention they built it, but supposed it to be by way of innovation, and for the introduction of strange gods, they did not incline to disbelieve it; but thinking this defamatory report, as if it were built for divine worship, was credible, they appeared in arms, as though they would avenge themselves on those that built the altar; and they were about to pass over the river, and to punish them for their subversion of the laws of their country; for they did not think it fit to regard them on account of their kindred or the dignity of those that had given the occasion, but to regard the will of God, and the manner wherein he desired to be worshipped; so these men put themselves in array for war. But Joshua, and Eleazar the high priest, and the senate, restrained them; and persuaded them first to make trial by words of their intention, and afterwards, if they found that their intention was evil, then only to proceed to make war upon them. Accordingly, they sent as ambassadors to them Phineas the son of Eleazar, and ten more persons that were in esteem among the Hebrews, to learn of them what was in their mind, when, upon passing over the river, they had built an altar upon its banks. And as soon as these ambassadors were passed over, and were come to them, and a congregation was assembled, Phineas stood up and said, That the offense they had been guilty of was of too heinous a nature to be punished by words alone, or by them only to be amended for the future; yet that they did not so look at the heinousness of their transgression as to have recourse to arms, and to a battle for their punishment immediately, but that, on account of their kindred, and the probability there was that they might be reclaimed, they took this method of sending an ambassage to them: "That when we have learned the true reasons by which you have been moved to build this altar, we may neither seem to have been too rash in assaulting you by our weapons of war, if it prove that you made the altar for justifiable reasons, and may then justly punish you if the accusation prove true; for we can hardly suppose that you, have been acquainted with the will of God and have been hearers of those laws which he himself hath given us, now you are separated from us, and gone to that patrimony of yours, which you, through the grace of God, and that providence which he exercises over you, have obtained by lot, can forget him, and can leave that ark and that altar which is peculiar to us, and can introduce strange gods, and imitate the wicked practices of the Canaanites. Now this will appear to have been a small crime if you repent now, and proceed no further in your madness, but pay a due reverence to, and keep in mind the laws of your country; but if you persist in your sins, we will not grudge our pains to preserve our laws; but we will pass over Jordan and defend them, and defend God also, and shall esteem of you as of men no way differing from the Canaanites, but shall destroy you in the like manner as we destroyed them; for do not you imagine that, because you are got over the river, you are got out of the reach of God's power; you are every where in places that belong to him, and impossible it is to overrun his power, and the punishment he will bring on men thereby: but if you think that your settlement here will be any obstruction to your conversion to what is good, nothing need hinder us from dividing the land anew, and leaving this old land to be for the feeding of sheep; but you will do well to return to your duty, and to leave off these new crimes; and we beseech you, by your children and wives, not to force us to punish you. Take therefore such measures in this assembly, as supposing that your own safety, and the safety of those that are dearest to you, is therein concerned, and believe that it is better for you to be conquered by words, than to continue in your purpose, and to experience deeds and war therefore."