In Parashat Toledot, we know that Eisav got very angry at Yaakov for stealing what he believed to be his blessing, and began planning to kill Yaakov once his father Yitzchak passed on. The specific wording used by Eisav is that he will kill Yaakov once the Aveilut, mourning period, is over. The Kli Yakar explains that Eisav didn't simply say he would wait for Yitchak to die, but used the specific word “Aveil” because he had the understanding that he would be able to kill Yaakov only within a close proximity to his mourning, as a mourner may not study Torah, and Yaakov would be left without merits from his Torah learning to protect him.
This isn't the first time that Eisav's knowledge of Torah assisted his deviousness. Rashi comments that the words used to describe Eisav (BeReishit 25:27), Yodeia Tzayid, one who knows trapping, actually means that Eisav knew how to deceive people with his words, such as when Eisav would ask a question about Torah to make Yitzchak think highly of him and his Torah learning. Eisav understood that once Yaakov started learning Torah again, he would be untouchable. These laws and powerful implications are also true for Yaakov's descendants, the Bnei Yisrael, as we too adopt the practice to not learn during Aveilut.
The study of Torah has ensured Bnei Yisrael's continued existence from one generation to the next. The Meshech Chochmah (Vayikra 26:44) explains that once we abandon it, the cycle of assimilation and persecution will continue, and ensure that we return to Torah study once again. Looking back at history, one can see over and over again that when the Jewish people forgot the importance of Torah study and observance, Nochrim reminded them one way or another. If Eisav, a lowly deceiver, realized the power and meaning behind Torah study, all the more so it should be apparent and recognized in our daily lives. May we all realize the true potential contained within Torah learning, and utilize it to avoid failing into Eisav's traps.
-Based on a Devar Torah given by Rabbi Aryeh Brueckheimer