In one the most famous passages in his commentary to Chumash, Rashi, in the beginning of Parashat Vayishlach, presents a novel interpretation to Yaakov's message to Esav. According to the plain meaning of the verse, Yaakov simply informs Esav, "I have lived with Lavan and have stayed until now" (32:5). Rashi, however, commenting on the words, "im Lavan garti" ("I have lived with Lavan"), writes, "I have lived with Lavan – and I have observed the six hundred and thirteen commandments, and I did not learn from his evil conduct." Yaakov here emphasizes to his brother that despite his lengthy stay in Lavan's home and prolonged exposure to his influence and lifestyle, he nevertheless retained his commitment to all six hundred and thirteen commandments.
Several later writers have noted the seeming redundancy in Rashi's comments. Once Yaakov affirms that he observed all the commandments during his stay with Lavan, why must he add, "and I did not learn from his evil conduct"? Is it not obvious than anyone who remains devoted to God's commandments does not look to Lavan as an example to follow?
One answer is cited in the name of the work, "Maskil El Dal," which explains that Yaakov tells Esav that he did not learn anything at all from Lavan – even the positive lessons tone could have potentially extracted from Lavan's conduct. Lavan's enthusiastic endeavors to earn wealth and the efforts he invested towards this end could have served as an example of the type of efforts one should invest in far more sacred pursuits. Yaakov here claims that he wished to learn nothing at all from Lavan and to distance himself entirely from his behavior – to the point where he did not even draw the lessons that he perhaps could have from Lavan's lifestyle.
Needless to say, this idea leaves unanswered the question of why Yaakov did not want to learn anything at all from Lavan. After all, as the famous mishna in Pirkei Avot (2:1) establishes, "Who is wise? He who learns from all men." Presumably, then, Yaakov had no reason to refuse to learn anything at all from Lavan.
In fact, Rav Meir Shapiro of Lublin suggested the diametrically opposite interpretation of this passage in Rashi. Yaakov here bemoans the fact that he did not learn anything from Lavan. Although he indeed observed the mitzvot, he failed to learn from Lavan's example of enthusiasm and effort in pursuing one's goals.
The most likely interpretation of this passage, however, would seem to be the explanation cited in the name of Rav Yaakov Ruderman zt"l. Yaakov Avinu proclaims that he succeeded religiously in Lavan's home in two areas: he did not forsake the commandments, and he did not adopt Lavan's culture and lifestyle. For it is entirely possible for one to remain fully committed to the strictest standards of mitzva performance while still acting like "Lavan," while still inculcating and adopting the very worst the surrounding culture has to offer. Benei Yisrael's challenge in exile, when it lives among the gentiles, including many "Lavans," is not only to continue our observance of the Torah, but also to continue our observance of the general ideals and lifestyle of the Torah. Yaakov could have adopted Lavan's general conduct and values while still performing the commandments; but instead, as he tells Esav, "I did not learn from his evil conduct," and he remained fully committed to the ethics, values and lifestyle of kedusha that he had received from Avraham and Yitzchak.