In the piyut recited on Yom Kippur, we say: “For we are Your children, and You are our Father.” The fact that we are children of our Father in Heaven creates an unbreakable bond between us and Him, regardless of what our spiritual condition may be. The possuk in Yeshayah (1:4) refers to Klal Yisrael as “corrupting children.” Although the children may have corrupted their ways, they nevertheless remain children of Hashem Elokeihem.
Rabbeinu, zichrono livrachah, asked that we find a seemingly puzzling difference between the nusach of the Birchos Krias Shema of Shacharis and those of Maariv. At Maariv we say, “His children beheld His might; they praised and gave thanks to His Name.” Yet at Shacharis, they are no longer referred to merely as children: “For this, the beloved praised and exalted Hashem, while the dear ones offered songs, praises and thanksgiving.” By the morning, the children have become “beloved” and “dear friends.” What is the meaning of this change?
Rabbeinu explained this based on the words of Pirkei D’Rabbi Eliezer (Chapter 41):
“The Mitzriyim pursued Bnei Yisrael until the Yam Suf and encamped behind them… while the sea stood before them. When Klal Yisrael saw the Mitzriyim, they became exceedingly frightened. At that moment, they cast away all the abominations of Mitzrayim, did a great teshuvah, and cried out to their G-d.”
We see from here that Klal Yisrael still clung to avodah zarah until the very last moment. Only when they stood before the Yam Suf, with nowhere to escape, did they finally do teshuvah.
With this, the difference in the nusach of the brachos is beautifully understood. When the Rambam describes the tremendous power of teshuvah, he writes (Hilchos Teshuvah 7:6):
“Teshuvah brings close those who were distant. Yesterday, this person was hated before Hashem, repulsive, distant and an abomination; today, he is beloved, cherished, close and a dear friend.”
Thus, on the night before Krias Yam Suf, Klal Yisrael were still worshipping avodah zarah. They were nevertheless called “children,” because even children who sin against their father still remain his children. But only in the morning, after they had done a great teshuvah and cast away the abominations of Mitzrayim, did Klal Yisrael merit the additional titles of “beloved” and “dear friends.”
The Rambam writes (Hilchos Teshuvah 3:4):
“The entire House of Israel is accustomed to increase its giving of tzedakah and its good deeds, and to engage in mitzvos from Rosh Hashanah until Yom Kippur, more than during the rest of the year.”
Rabbeinu, zichrono livrachah, was asked why the Rambam does not mention increasing one’s Torah learning during this time. He answered that Torah learning is included in the Rambam’s words, “to engage in mitzvos.” The reason the Rambam specifically singles out and mentions the mitzvah of tzedakah is because there is a special inyan to increase one’s tzedakah during these days. (Derech Sichah)