The Amidah and God's (and our) freely given love

I was studying last week about the Amidah with a colleague. According to the rabbis, the patriarchs originated the three daily amidahs. That's one of the reasons the prayer begins with "God of Abraham, Isaac and Jacob." Yet, how could the patriarchs have established this prayer when the Torah was not even given until hundreds of years after their lives?
I read a new answer, credited to Rabbi Nosson Sterhartz, the recorder of the Bratzlaver Rebbe. Even before the Torah was revealed, there was divine hesed or love. This is the basis of the Torah and in fact, the basis of all creation. Abraham and Sarah prayed to God through this love - they served God in deed and word - experiencing God's love in their lives and reciprocating it with kindness and spirituality. The core of this "service" was 'chesed hinam' or freely given love, love without any thought of return.
This was the foundation of Abraham's life and his legacy to us today. Abraham welcomed strangers. Abraham refused reward for rescuing captives. Abraham tried to save the evil citizens of Sodom. Abraham brought others closer to God. Abraham was a blessing to the world - to people who he touched with his own piece of God's love. Abraham knew of "freely given love" even before the Torah was given. Since Abraham blessed the world with this aspect of the divine, we begin the Amidah with his name and his children's ... who continued this precious, holy legacy. We we rise to recite the Amidah, we, Abraham's children, invoke the source of our prayer: unconditioned, freely given love.