Verse 2: And Joshua said unto all the people, Thus saith the LORD God of Israel, (Gen. 11:26, 31; Judith 5:6, 7) Your fathers dwelt on the other side of the flood in old time, even Terah, the father of Abraham, and the father of Nachor: and (Gen. 31:53) they served other gods.
Unto all the people, that is, that people which were present, to wit, to the elders, etc., by whom it was to be imparted to all the rest, and to as many of the people as came thither.
[Thus saith the Lord] That is, through me (Vatablus).
[The God of Israel] This exordium is perfectly suited to the following narration, since the whole of it is taken up in explaining the goodness of God toward the family of Israel (Masius).
[Across the river] That is, Euphrates; which Jonathan and the Syriac have here. [All interpreters agree.]
The flood, or, the river, to wit, Euphrates, as all agree; so called by way of eminency.
[Your fathers…and they served strange gods] He shows that he speaks of their near ancestors, not of the more remote, of which sort were Shem and Noah. This is done, so that it might be evident that they were graciously adopted by God for a people, not only freely, but even while they were enemies (Masius).
[Terah, the father of Abraham and Nachor] He names these, because from these the entire stock of Israel was descended. For from Nahor the maternal lineage is traced through Rebekah, Leah, and Rachel (Masius). Question: Whether Abraham also worshipped idols? Response: Some deny this (thus Lapide, Tostatus and Cajetan in Serarius, Pererius in Lapide). Some affirm that he, when he was younger, was an idolater (thus Masius, Serarius out of the Rabbis). And there are those that think that for that reason Abraham was called ἀσεβῆ/ungodly, Romans 4:5 (Serarius). I am not able to heed those that with great effort seek to vindicate Abraham from this sin, I know not with what arguments. But, supposing that to be the case, the grace of God, with which He embraced him, would not be the more illustrious, the more sinful he was; and not for the admirable kindness of God would the Sacred History commemorate and inculcate so many times in our souls, that He rescued him, as if taken by the hand, from his homeland and the company of idolaters, as we called them (Masius, similarly Malvenda). Concerning this question see what things we have on Genesis 12:1 (Bonfrerius).
They served other gods, that is, both Abraham and Nahor were no less idolaters than the rest of mankind. This is said to prevent their vain boasting in their worthy ancestors, and to assure them that whatsoever good was in or had been done by their progenitors, was wholly born God’s free grace, and not for their own merit or righteousness, as the Jews were very apt to conceit.
 Hebrew: וַיֹּ֙אמֶר יְהוֹשֻׁ֜עַ אֶל־כָּל־הָעָ֗ם כֹּֽה־אָמַ֣ר יְהוָה֮ אֱלֹהֵ֣י יִשְׂרָאֵל֒ בְּעֵ֣בֶר הַנָּהָ֗ר יָשְׁב֤וּ אֲבֽוֹתֵיכֶם֙ מֵֽעוֹלָ֔ם תֶּ֛רַח אֲבִ֥י אַבְרָהָ֖ם וַאֲבִ֣י נָח֑וֹר וַיַּעַבְד֖וּ אֱלֹהִ֥ים אֲחֵרִֽים׃
 Judith 5:6, 7: “This people are descended of the Chaldeans: And they sojourned heretofore in Mesopotamia, because they would not follow the gods of their fathers, which were in the land of Chaldea.”
 That is, the introduction.