http://revach.net/article.php?id=4810

Section:  Avodah   Category: Chanoch L'Naar
Parshas Vayeitzei: Steipler Gaon - When Your Whole Dream Is Less Bad

Rashi (Vayeitzei 29:11) brings Chazal who say that Yaakov cried when he saw Roche because he came empty handed without gifts. The reason was because Elifaz was commanded by his father Eisav to kill Yaakov, but since Elifaz was a talmid of Yitzchok he reached a compromise where he left Yaakov penniless which is considered like dead.

The Shnayim Mikra brings in the name of the Steipler Gaon that we see an important lesson from here. Yitzchok invested a great deal of time teaching Elifaz the son of Eisav. For what? So that he will only be a Ganav and not a murderer. The lesson is do not give up on those who are destined to lead lives contrary to the Torah. Even if your teaching can at best minimize the aveiros that he will commit it is still worth it!