Daf 11. Gemara. The Gemara wonders why Beit Shammai interprets When you lie down and when you rise differently than Beit Hillel. The discussion illustrates how the rabbis derive definite conclusions from ambiguous Scriptural language. Beit Shammai uses the verse When you walk along the way to derive the rule that a groom is exempt from reciting the evening Shema on his wedding night if he is marrying a virgin. The Gemara asks why a groom who marries a widow is not exempt. Answer: “One who marries a virgin is preoccupied by his concern lest he discover that his bride is not a virgin, while one who marries a widow is not preoccupied.” Even so, not all who are “preoccupied” are exempt– the mourner remains obligated.
Rav Yehezkel taught that both Hillel and Shammai agree that anyone who follows the opinion of the other fulfills his obligation, but Rav Yosef said that one who acts by Shammai’s opinion “has done nothing,” and Rav Nachman bar Yitzhak says that one who acts by Shammai’s opinion incurs the death penalty. (This last opinion explains the rebuke of Rabbi Tarfon in yesterday’s daf.)
Mishna. Here we have the order of the blessings that surround the Shema. Also, “Where the Sages said to recite a long blessing, one may not shorten it . . . a short blessing, one may not lengthen it.”
Gemara. The content of the blessings is discussed. It is debated whether or not one must recite a blessing when studying halakha that is not based on verses of Torah. “And Rav said: Even for Talmud.”
Comment. Hillel and Shammai’s arguments were settled long before the Talmud was transcribed, but traces of the bitterness are detectable in this daf in Rav Nachman bar Yitzchak’s harsh decree that followers of Shammai deserve the death penalty. A less inflammatory version of this is reflected elsewhere in the more well known formulation that the halakha follows Hillel in this world and Shammai in the World to Come. As far as I know, it is never explained why more stringent rules would be necessary in the next world. Perhaps there are temptations on the other side that we poor mortals cannot possibly imagine!