Komentaryong Sumisipi para sa Jeremias 29:12

Pesukim 2 and 3 suggest that Daniel realizes that the time of the seventy-year redemption has arrived, but yet Daryavesh HaMadi has done nothing to allow the Jews to return to Eretz Yisrael and rebuild the Beit HaMikdash. Therefore, Daniel calls out in Tefillah, accompanied by fasting, to Hashem in a plea to bring about the redemption. Yirmiyahu HaNavi (Yirmiyahu 29:12-13) indeed teaches that Hashem redeems us after seventy years only if we reach out to him in Tefillah¹¹⁷The end of the seventy years is, as apparent from Yirmiyahu 29:12-13, an Eit Ratzon, a most auspicious opportunity for our Tefillot to be answered by Hashem. The same opportunity presents itself on Mondays and Thursdays, which are also an Eit Ratzon since according to the Midrash Tanchuma to Breishit 19:24 (cited by Tosafot to Bava Kama 82a s.v. Kdei) it was a Thursday when Moshe Rabbeinu ascended Har Sinai to receive the second Luchot and it was a Monday when he returned. Therefore, in our lengthy Tachanun on Mondays and Thursdays we say Daniel’s Tefillot at length..

Meriting Ge’ula
Finally, just because the seventy years have expired and the Babylonian empire has ended, does not automatically mean that the Ge’ulah will ensue. Daniel in Perek 9 prays for the return to Yerushalayim and this Tefillah seems to have influenced Hashem to tilt the events in favor of Koresh permitting us to return. After Yirmiyahu HaNavi sets forth the seventy-year terminus of the exile (Yirmiyahu 29:10), he notes (Yirmiyahu 29:12-13) that we will return only if we trigger the redemption with our Tefillot.