Why will He whistle for them?
Rashi: This is a sign that one who errs in the path should come to him.
Radak: This is a sign of calling. The same applies to "v'Sharak Lo mi'Ktze ha'Aretz" (Yeshayah 5:26).
Malbim: This is for Bnei Yehudah, who were scattered among the nations and subjugated in Galus. I will whistle for a sign that they return to Eretz Yisrael.
When will He gather them?
Rashi: At the time of the Ketz, in the future.
Radak: Due to the afflictions that Malchei Yavan did to them, they were scattered among the nations. In the days of the Chashmona'im, they returned to Eretz Yisrael.
Did He already redeem them?
Rashi: This will be when He redeems them.
What do we learn from "v'Ravu Kemo Ravu"?
Rashi: They will increase in Galus like they increased in Egypt.
Radak: Like they increased in Egypt, so they will increase at that time.
Malbim: During the Galus, they were constantly diminished via pretexts and murders. Now they will increase like beforehand.
