1)
When will He have mercy on Beis Yehudah?
1.
Rashi: This will be after He ceases kingship from Yisrael. From when the 10 tribes were exiled, there was mercy on Beis Yehudah, from Chizkiyah until Tzidkiyah. Radak ? Malchus Yehudah stood from the Galus of Yisrael in Chizkiyah's sixth year until the Churban.
2)
How will He save them without weapons, war, horses or cavalry?
1.
Radak: He saved them from Sancheriv. Hashem's angel struck Machaneh Ashur, like it says (Melachim II, 19:35). Malbim ? this shows that they are still My nation, and the mother is My wife.
