From when is "mi'Ymei ha'Giv'ah"?
Rashi (citing Seder Olam 12): It is from the days of Pilegesh b'Giv'ah, in Binyamin. It was in the days of Osni'el ben Kenaz, the first Shofet, in the days of Kushan Rish'asayim. Pesel Michah was in his days.
Radak: Shevet Binyamin endangered themselves to support the foul deed. Also the other Shevatim were punished because there were idolaters among them.
What is "Chatas Yisrael"?
Rashi: The Tes in Chatas is soft (has no Dagesh); it is feminine 1 past tense, like Ast, Bos. (You, Yisrael, sinned.)
Malbim: It is idolatry.
Minchas Shai: In Rashi's text, there is a Sheva under the Sov; this shows that it is feminine. The soft Tes proves that it is past tense (PF). Why does Rashi mention "Azlas Yad"? It is not second person feminine!
What do we learn from "Sham Amadu"?
Rashi: They had this Midah from then.
Rashi citing Targum Yonasan: There they rebelled against My word and appointed Sha'ul 1 [to be king].
Radak: It is as if the sinners in this generation stood there, for they persist in their evil, and do not repent. This is like it says above "Hemiku Shichesu ki'Ymei ha'Giv'ah" (9:9).
Malbim: Bamos and idols were in Dan from of old. It was already established as a place of idolatry from when they established Pesel Michah there. Therefore Yaravam put one of the calves in Dan. Chazal said, this is why Bnei Yisrael did not succeed the first two times that they fought in Giv'ah (against Binyamin), amidst Kin'ah for Zenus, because they did not have Kin'ah for Pesel Michah.
What is the meaning of "Lo Sasigem ba'Giv'ah Milchamah..."?
Rashi: Because they had the sin of idolatry and they were not adamant about it, they did not succeed in the war in Giv'ah against Binyamin 1 .
Radak: They think in their hearts that war will not catch them, like it caught the sinners in Giv'ah, when Yisrael came to Bnei Avlah, i.e. Bnei Binyamin. They were eradicated in their sin. So these will be eradicated in their sin; the enemy's sword will catch them. They should not think that it will not catch them!
Malbim: The war that they fought against Bnei Avlah (Binyamin), it did not reach the Bamos of Pesel Michah. They stood. They did not nullify them then! This shows that Yisrael already veered after idolatry - therefore they had no Kinah against it.
The first two times that they fought, Binyamin defeated them. (PF)
What are "Bnei Alvah"?
Rashi: [Bnei Binyamin] are haughty. They made themselves Elyonim (supreme), and did not heed their brothers to give (let Yisrael kill) Bnei ha'Giv'ah (Shoftim 20:13).
Radak: This is like Bnei Avlah; the letters are reversed. The same applies to Zeva'ah-Za'avah, Keves-Kesev, Simlah- Salmah.