In the midst of recruiting Moshe to be His messenger to take Bnei Yisrael out of Egypt, Hashem tells Moshe that after the nation’s living and working for so long in Egypt, Hashem has finally heard their cries: “VeAtah, Hinei Tzaakat Bnei Yisrael Ba’ah Eilai,” “And now, behold, the cry of Bnei Yisrael has come to me…” (3:9). This raises a glaring question: why did it take so long for Hashem to hear the cries of the Jewish slaves? Does He not hear everything? The sobbing would seem to have been going on for some time; if so, Hashem must certainly have heard it a long time ago! Why does it say that Hashem only now hears their cries?
In fact, the answer was already partly indicated earlier in Sefer Bereishit at the Brit Bein HaBetarim, when Hashem told Avraham that the Jewish people would be in a strange land for 400 years. Hashem foretold that during those years there would be a period of slavery, and, of course, that Avraham’s descendants would be redeemed from that slavery. In our Pasuk, Hashem is telling Moshe that although the 400 years have not yet been fulfilled, the time for redemption has nonetheless arrived “now.” Because of Bnei Yisrael’s cries, Hashem decided the appropriate time has come.
The traditional commentaries offer a number of reasons for Hashem’s acceptance of these cries at this time. According to Ibn Ezra, Bnei Yisrael did Teshuvah, whose power we are all familiar with. Seforno explains that the word “now” in the Pasuk teaches us that the Tefillot were said “in truth.” Similarly, Chizkuni says the Tefillot are justified as Hashem sees their oppression. Indeed, many agree that Hashem is convinced that the time of redemption has arrived because Bnei Yisrael’s cries are coupled with superfluous oppression by the Egyptians (see Rashi). Thus, despite the fact that the predicted 400 years are not yet complete, Hashem now has reason enough to redeem Bnei Yisrael.
In summary, Hashem makes two very strong arguments to Moshe Rabbeinu to explain why the time of liberation has arrived. First, Bnei Yisrael have merited it through Teshuvah and sincere Tefillot. Second, their oppressors have exceeded their role, and are about to be punished. As Rav Shimshon Raphael Hirsch writes, Moshe must realize that Bnei Yisrael are crying out to be saved and Hashem is willing to save them now. This alone should be enough for Moshe to accept his job as Hashem’s messenger.