In this week's parashah (34:25), the Torah tells us that when Shimon and Levi attacked Shechem, they had bitachon. As it states, ויבאו בטח העיר אל , "They came to the city with bitachon..."
Shimon and Levi were two people against an entire city. What were their chances? We would assume that they would be trembling from fear. But the Torah tells us that they came בטח with a feeling of security, confident that Hashem would help, and indeed, He did.
Rashi writes, "They were confident [they would win the war] because the people of Shechem were in pain [and weak from the milah]."
Rashi quotes a Midrash that states another reason they were confident they would win the war. "The Midrash says that they trusted in the strength of the old one (של כחו על היו בטוחים זקן)."
Who was "the old one" they trusted? Some meforshim say that Rashi means they trusted in Yaakov Avinu's strength. The Midrash (Bereishis Rabba 80) states, "Yaakov Avinu didn't want that his children should [wage this war against Shechem]. But after they did so, he said to himself, 'Will I allow my children to fall into the hands of the goyim?'
"What did Yaakov do? He took his sword and bow and stood at the entrance of Shechem. He said, 'If the nations will come to fight with my children, I will fight with them...'"
Shimon and Levi were confident this would happen, and they trusted that Yaakov's great strength would save them. Others explain that Shimon and Levi trusted in Avraham Avinu's tefillos. Because Avraham Avinu davened for them, as it states (Bereishis 12:6), שכם מקום עד בארץ אברם ויעבור, "Avram passed through the land until Shechem." Rashi writes, "Avram went there to daven for Yaakov's children who will fight a war with Shechem."
The avos foresaw the future of the Jewish nation, and they davened for their success. Avraham knew that his descendants would wage a war in Shechem, so he davened for them. Shimon and Levi relied on his tefillos.
The Meor Einayim (Miketz) writes, "It is known that the avos davened during their lifetime for what will occur in the future up to when Moshiach will come, may it be speedily in our days."
For example, at akeidas Yitzchak, Avraham said (Bereishis 22:5), ה"כ עד נלכה והנער ואני, and ה"כ hints to כסלו ה"כ, the date of Chanukah. The Meor Einayim explains, "Avraham davened they should win the war against the Yevanim in the days of Matisyahu.
"Yosef HaTzaddik spoke to Binyamin and said (Bereishis 43:29), בני יחנך אלקים. יחנך hints to חנוכה. [Yosef davened] that Hashem should perform miracles on Chanukah."
The avos davened for our generation, too. We can be certain that our adherence to Yiddishkeit until today is mainly in the merit of the avos's tefillos. As the Meor Einayim writes, "Our ability to be strong in Torah and mitzvos is all because our forefathers davened for us."
Shimon and Levi trusted that Hashem would help them in the merit of Avraham's tefillah. As Rashi writes, זקן של כחו על היו בטוחים."
