Verse 11: And the children of Israel (Deut. 13:12, etc.; Judg. 20:12) heard say, Behold, the children of Reuben and the children of Gad and the half tribe of Manasseh have built an altar over against the land of Canaan, in the borders of Jordan, at the passage of the children of Israel.
[And when the children of Israel had heard] The law of the corporate body is unto all its parts, and the greater part maintains the law of the corporate body. See Deuteronomy 13:12, and Concering the Law of War and Peace 2:5:17 (Grotius).
[In the land of Canaan, upon the banks of Jordan, over against the children of Israel, אֶל־מוּל֙ אֶ֣רֶץ כְּנַ֔עַן אֶל־גְּלִילוֹת֙ הַיַּרְדֵּ֔ן אֶל־עֵ֖בֶר וגו״] Over against (or, in the view of [Osiander], or, upon the borders of [Septuagint]) the land of Canaan, over against the children of Israel (Tigurinus, Osiander, Bonfrerius). Others: on the side, or, toward the side, of the children of Israel (Jonathan, Munster), on the portion of the side of the children of Israel (Arabic). Others: at the passage, or, toward the passage, of the children of Israel (Septuagint, Montanus, Junius, Pagnine, English). Over against, that is, in such a way that this altar was in the midst of the Gileadites and the Canaanites, and joined the former with the latter, and associated them in the religion and law of sacrifice (Lapide). Question: Where was this altar? Responses: 1. On the farther bank of Jordan, or in Gilead (Jonathan in Bonfrerius). 2. Rather on the nearer bank, or in the land of Canaan (Lapide, Bonfrerius, Menochius, Drusius). The reason is that they were wanting to testify by this altar to their original right that they had in the land of Canaan, especially to sacrifice on th altar of the Temple, common with the other nine tribes (Lapide). Of which unique altar this was a symbol, that among their descendants it might testify that they worshipped, and are obliged to worship, the same God with them in the same sacred rites (Masius).
At the passage of the children of Israel: Where they passed over Jordan, either at their first entrance into Canaan, or afterwards, and usually.
Verse 12: And when the children of Israel heard of it, (Judg. 20:1) the whole congregation of the children of Israel gathered themselves together at Shiloh, to go up to war against them.
The children of Israel; not in their own persons, but by their elders, who used to transact all affairs of this kind in the name and stead of all the people.
[They gathered together, etc.] Just as zeal for the vindication of Religion is worthy of praise; so also it is worthy of great reprehension that with a rash judgment they altogether condemn that which they have known with insufficient investigation. But it is well that, with their thoughts first gathered, they take counsel concerning first becoming acquainted with the intention of their brethren, etc. Let us learn not rashly to be moved with suspiciouns concerning the words and deeds of our brethren. Judge not, etc., Matthew 7:1, 2. It is asked here whether under the new Law Religion might be vindicated with the sword. Response: What the old Law determined is evident from Deuteronomy 13. Moreover, no more by the Law of Christ than by the Law of Moses was the salvation of the honest obliged to be advanced through the impunity of the wicked, since there was one and the same end for both Laws, namely, love toward God and one’s neighbors. But by the Gospel of Christ are men liberated for freedom and impunity of wickedness? And what sin is greater than for one to defect from true Religion, and to go to lead others away? Now, I do not speak of those that in the study of piety turn a little from the Religion of the fathers, and follow, not so much diverse doctrines, as certain rites; but of those that overthrow the very foundations of Religion, and are not able to be moved from their wickedness by any arguments (Masius).
[So that they might fight against them] As against transgressors of the Law, because God had commanded that there be only one place, and on altar, of sacrifices for the people of Israel, Exodus 20:24; Leviticus 17:8, 9; Deuteronomy 12:5, 11, 13 (Menochius).
To go up to war against them; as apostates from God, according to God’s command in that case, Deuteronomy 13:13, etc.
 Hebrew: וַיִּשְׁמְע֥וּ בְנֵֽי־יִשְׂרָאֵ֖ל לֵאמֹ֑ר הִנֵּ֣ה בָנ֣וּ בְנֵֽי־רְאוּבֵ֣ן וּבְנֵי־גָ֡ד וַחֲצִי֩ שֵׁ֙בֶט הַֽמְנַשֶּׁ֜ה אֶת־הַמִּזְבֵּ֗חַ אֶל־מוּל֙ אֶ֣רֶץ כְּנַ֔עַן אֶל־גְּלִילוֹת֙ הַיַּרְדֵּ֔ן אֶל־עֵ֖בֶר בְּנֵ֥י יִשְׂרָאֵֽל׃
 Hebrew: וַֽיִּשְׁמְע֖וּ בְּנֵ֣י יִשְׂרָאֵ֑ל וַיִּקָּ֙הֲל֜וּ כָּל־עֲדַ֤ת בְּנֵֽי־יִשְׂרָאֵל֙ שִׁלֹ֔ה לַעֲל֥וֹת עֲלֵיהֶ֖ם לַצָּבָֽא׃