The Rav discusses the two covenants- the Patriarchal and the Sinaitic. 
The Patriarchal Covenant was made with Avraham and Sarah as a unit. When Sarah dies, Avraham's role is completed. The Torah tells us very little about Avraham's life after Sarah dies.  He recedes to the background until Yitzchak is married and takes his place along with Rivka as the next generation of the Patriarchal Covenant. The Rav discusses the 'bechi and hesped' of Avraham when Sarah dies.
 
He discusses the famous Rashi regarding the years of Sarah- 100, 20, and 7. The Rav explains that one can discuss these three stages in connection with Avraham as well. He develops the idea that the three stages reflect 3 basic or fundamental aspects of a Jew's Avodas Hashem. 100- Talmud Torah. One is older and can think conceptually and discriminate between ideas. 7- Tefillah. The Rav gives an example of a young, bright child who suspends his own judgement and follows his parents. A Jew in prayer should approach Hashem as a child approaches a parent. 20- Gevurah. Avraham uses his strength to act morally and ethically to save Lot from harm.
 
When Avraham performed the Akeidah, he suspended his own thinking to follow Hashem's Will. We have to do something similar and surrender to the Will of Hashem and accept all of the Mitzvot completely. 
 
In general, history is governed by rules of causality. One event leads to another or begets another. In contrast, the Jewish People live based on destiny. Destiny is the root of destination. We are heading for a destination. The cause is not the past but the future. For example, we yearn for Eretz Yisroel because it is the Promised Land.