The Gemara tells us that from the beginning of our parsha, we see that Yaakov Avinu was the originator of our evening prayer, Maariv. Maariv is unlike Shacharit and Mincha in that the Maariv prayer has no Korban that corresponds to it. For this reason, the Gemara debates whether or not Maariv is obligatory or simply "optional." This Ten deals with this debate and its practical relevance to how we end our day.