"Artzah Sayeer" (Perek Lamed Bais Pasuk Daled). The Chumash tells us that Yaakov sent messengers to his brother Esav, in the land of Sayeer. Rashi explains that the word "Artzah" means to the land. He brings down a Klal, a rule, from the Medrash that every word that requires a "Lamed" (meaning to) at the beginning, can instead have a "Hey" at the end.
What is interesting is that the Medrash brings this rule earlier in Parshas Vayetze on the words "Vayelech Charanah" (Perek Chof Ches Pasuk Yud). So the question we can ask is why does Rashi bring the Klal here in Vayishlach and not earlier in Vayetze.
The answer to this question lies in the topic being discussed in this section of the Parsha. Yaakov was preparing to meet Esav, to have a confrontation. Rashi brings us a Klal, for dealing with confrontations. "Kol Tayva," the word "Tayva" means word, but the Gemara also uses it as a Lashon Hatzalah, to save. In the story of Noach it was the Tayva that saved them. "Kol Tayva Shzireecha Lamed," every time you need saving you may think you need a Lamed. Rabbi Akiva tells us that the Lamed is a remez to strength. This is because Lamed is the largest of all the letters. You may think you need to confront with strength, not so says Rashi. "Hey Bsofa" add a Hey at the end. The letter Hey is a remez to Teshuva, Chazal tell us that the word Teshuva is "Tashuv Hay," returning to Hey. The Hey is small and modest, which is what we become when we do Teshuva.
Rashi is telling us that when we go in to a confrontation with the Goyim, we should go not with strength but rather with Teshuva.