What do we learn from "Ki Na'ar Yisrael va'Ohavehu"?
Rashi (10:15): All this [punishment] was because when Yisrael was a youth, and I loved them, they were Menu'ar (empty) of all good. Radak - this is when Yisrael were in Egypt. Therefore, I am upset with them more than other nations, for I loved them from their youth and saved them from their enemies. When they transgress My Mitzvos, it is upon Me to afflict them, like a man afflicts his son.
How did Hashem call to His son from Egypt?
Rashi: Via His Nevi'im - they told [Yisrael] to cling to His Torah.
Radak: He called to Pharaoh due to Yisrael, His son. He said "Bni Bechori Yisrael; Shlach Es Bni va'Ya'avduni" (Shemos 4:22-23). From when they were in Egypt, He called Yisrael His son.
Malbim: I called to My son, even though he did not call to Me. I called with love that he should come to Me, like a father loves his son, and calls him to come to him. The son does not call to his father.