1)
What is the meaning of "la'Shav Hikisi Es Beneichem"?
1.
Rashi: It was for naught. You did not take Musar (learn from it).
2.
Malbim: Your children are not culpable. They had no one to learn Musar from!
2)
Why did He say "Achlah Charbechem Nevi'eichem"?
1.
Rashi: You killed Zecharyah and Yeshayah.
2.
Malbim: You killed the Nevi'im who prophesized for you Musar and rebuke, until those who teach Musar ceased. Therefore, your children had no one to learn Musar from.
