In this week's parsha we see how Yaakov Avinu employed a three-pronged strategy in preparation for the confrontation with his brother Esav: battle, prayer, and tribute.

At the conclusion of his prayer Yaakov says as follows, "And You had said, 'I will surely do good with you, and I will make your offspring like the sand of the sea which is too numerous to count(Bereishis,32,13).'"

Rashi notes that although Hashem had directly promised Yaakov, "and your offspring will be as the dust of the earth," Hashem had made the aforementioned promise to his grandfather Avraham in reference to Yaakov.
Why did Yaakov refer to the promise made to Avraham rather than to the promise made directly to him?

Another peculiarity is that at the beginning of Yaakov's prayer he says, "Rescue me, please, from the hand of my brother, from the hand of Esav, for I fear him lest he come and strike me down, mother and children."

Why did Yaakov Avinu have to pray specifically for salvation "from the hand of Esav"? He had already asked for salvation "from the hand of my brother," and he only had one brother so either part of the prayer should have sufficed.

Reb Yoshe Ber Soloveitchick, the Beis HaLevi, explains that Yaakov's prayer was twofold. Firstly, he requested salvation from the hand of Esav, who still harbored hatred and desired to kill him. And secondly, he prayed for salvation from the hand of his brother, who might demonstrate brotherly love and cause Yaakov to become enamored with him, but ultimately, Yaakov would be in danger of falling victim to the negative influences of Esav's culture.

This insight sheds light on Yaakov Avinu's decision to utilize Hashem's promise to his grandfather Avraham Avinu in his prayer. Yaakov Avinu viewed that promise as a dual one: a promise of quantity, "I will make your offspring too numerous to count," and a promise of quality, "I will make your offspring as the sand of the sea."

Day after day, week after week, the waves of the sea pound against the sand that contains them, yet the sand remains unchanged. The water has no impact on the sand, but dust, on the other hand, turns immediately into mud when it comes in contact with water.

Therefore, Yaakov Avinu referred to the promise Hashem made to Avraham Avinu in praying that the offspring of Avraham possess the quality of sand so that they will be able to withstand the negative influences of Esav's culture.

May Hashem continue to protect us from the hands of our "brothers" and from the hands of the descendants of Esav.