Gathered themselves together - The various tribes had already dispersed to their homes, and were now summoned together again.

To go up to war against them - Supposing that they had built this altar in opposition to that which Moses, by the command of God, had erected, and were consequently become rebels against God and the Israelitish constitution, and should be treated as such. Their great concern for the glory of God led them to take this step, which at first view might appear precipitate; but, that they might do nothing rashly, they first sent Phinehas and ten princes, one out of each tribe, to require an explanation of their motives in erecting this altar.

And when the children of Israel heard of it,.... Of the building the altar in the above place, namely, the nine tribes and a half settled in the land of Canaan:

the whole congregation of the children of Israel gathered themselves together at Shiloh; where the tabernacle and altar of the Lord were, whose cause they undertook to avenge, being injured as they imagined by the altar the other tribes had built, and where they could consult the Lord by Urim and Thummim, if needful; hither they repaired from the several places around, where their tribes were settled; not the whole body of the people, but their heads and representatives:

to go up to war against them; to consult about it, and to prepare for it, which they were obliged to do by the law of God, as in the case of a city, so of a tribe drawn aside to idolatry; and which they imagined was the case of these tribes, or at least what they had done had a tendency to apostasy from the true worship of God, which they were zealous to defend at the hazard of their lives, and though it should issue in an extirpation of one or more of their tribes; see Deuteronomy 13:12.

And when the children of Israel heard of it, the whole congregation of the children of Israel gathered themselves together at Shiloh, to go up {g} to war against them.

(g) Such was their zeal, that they would rather lose their lives, that allow the true religion to be changed or corrupted.

22:12 The children of Israel - Not in their own persons, not by their elders, who used to transact all affairs of this kind in the name of all the people. Against them - As apostates from God, according to God's command in that case, Deut 13:13. and c.

22:10-20 Here is the care of the separated tribes to keep their hold of Canaan's religion. At first sight it seemed a design to set up an altar against the altar at Shiloh. God is jealous for his own institutions; we should be so too, and afraid of every thing that looks like, or leads to idolatry. Corruptions in religion are best dealt with at first. But their prudence in following up this zealous resolution is no less commendable. Many an unhappy strife would be prevented, or soon made up, by inquiries into the matter of the offence. The remembrance of great sins committed formerly, should engage us to stand on our guard against the beginnings of sin; for the way of sin is down-hill. We are all concerned to reprove our neighbour when he does amiss, lest we suffer sin upon him, Le 19:17. The offer made that they should be welcome to come to the land where the Lord's tabernacle was, and settle there, was in the spirit of true Israelites.