This is already written in verse 1! Why is it repeated?
Malbim: Above, Hashem merely informed Yehu - "Lo Ya'aseh Hashem Davar Ki Im Gilah Sodo" (Amos 3:7). After Basha died 1 and his son ruled, two generations sinned; it was time for the decree to be fulfilled (like we find aft Yaravam's son succeeded him), and Yehu was sent to make the decree known. This is why it says "b'Yad Yehu." "El Beiso" refers to his son Elah.
Does not "El Basha" imply that Hashem told Yehu to tell Basha in his lifetime?! (PF)
Why does it say "v'Gam b'Yad Yehu
Rashi: Yehu's Nevu'ah about Basha applied also to Basha's son Elah.
Radak: Even though verse 6 said that Elah ruled in place of Basha, it was not a full kingship. He ruled only two years, and not even complete years (refer to 16:10:1:1)! "V'Gam" equates it to Yaravam. Just like Achiyah ha'Shiloni prophesized that Yaravam's kingship would not last, and so it was - his son Nadav ruled only two incomplete years (refer to 15:33:1:1) - also regarding Basha.
For what evils will they be punished?
Malbim: (a) Since they were like Beis Yaravam, they should be punished like Beis Yaravam. (b) Since they were like Beis Yaravam, they had no right to kill him, and will be punished for this.
Why does it say that Basha killed "Oso" (Yaravam)? He killed Nadav!
Radak: "Oso" refers to Nadav. Even though he was not mentioned, Beis Yaravam was mentioned.
There was a Nevu'ah that Beis Yaravam must be killed out (15:29). Why was Basha punished for this?
Rashi: Basha sinned like Yaravam, therefore he was not allowed to kill his house, and was punished for this. Also "u'Fakadti Es Demei Yizre'el Al Beis Yehu" (Hoshe'a 1:4) - since they did not veer from Achav's ways, they were punished for killing them. 1
Ralbag (15:29): Basha did not kill them due to Yaravam's sin, for also Basha sinned like him! Rather, he wanted to remove anyone who could contest his kingship. Yehu was not punished for killing Beis Achav, for he did so like Hashem commanded 2 (Melachim II, 9:7). Malbim (15:29) - it was Hashgachah that Basha killed all Beis Yaravam. (He did not intend for Hashem's command.)
Hashem rewarded Yehu for killing Beis Achav (Melachim II, 10:30)! Alshich (Hoshe'a 1:4) - he was rewarded for the action, which fulfilled Hashem's will, but punished because it was not l'Shem Shamayim, for also he sinned. Metzudas David (1:4) - initially, Yehu killed them bi'Dvar Hashem, for worshipping the Ba'al. Later, Yehu sinned, and it was considered that he spilled innocent blood.
Hoshe'a 1:4 says that Beis Yehu will be punished for killing Beis Achav! Refer to 16:7:5:1*.
