Ya'akov sent messengers to his brother Eisav, to the land of Seir in the field of Edom. He instructed them saying, thus shall you say:[*] "To my lord Eisav, your servant Ya'akov says, 'I have lived ( גַּרְתִּי ) with Lavan until now..."Rashi comments: Another explanation: גַּרְתִּי has the numerical value of 613. That is to say: I lived with the wicked Laban, but I kept the 613 commandments, and I did not learn from his evil deeds.
A nice sentiment, but the way it's constructed is problematic. Even if we presume that Ya'kov had complete knowledge of the Torah that would not be revealed for another few hundred years, a great many of the 613 commandments can only be kept in the land of Israel. Others apply to priests only, or to farmers only, and so on. A shepherd living in exile, like Ya'akov, could not have kept all 613 commandments, so why is his claim presented in these terms?
Update (per Rob's request)
No doubt Rashi knew that Yaakov could not have kept all 613 commandments, but the language he chose to use here has misled legions of school children. You don't have to try very hard to find adults who imagine that the words "im Lavan garti v'tarya mitzvot shomarti" appear in the text itself and the Ya'akov kept every commandment.
[*] The cantillation markings in the Masoretic text put the sentance this way: He instructed them saying, thus shall you say to my lord Eisav: "Your servant Ya'akov says..." However scholars have demonstrated "To my lord Eisav, your servant Ya'akov says..." precisely follows the formula of salutation of ancient near Eastern letters, and so must be part of the message.