Tractate Berachot, Chapter 6, Tosefta 14

Notes:

1. The Tosefta states a new law regarding Berachot. It is not related to any Mishna. It is possible that this law is stated here specifically, bcause it mentions the Beracha of Shehechiyanu in it which is also mentioned in Mishna 3 of chapter 9.
2. This is equally applicable to a Torah Mitzvah or a Rabbinical Mitzvah. See Talmud Bavli (Shabbat 23a).
3. Generally the Beracha is said right before the Mitzvah is performed and not after. There is one exception to this rule, that of a convert who dips himself in the Mikvah for his conversion. Since the convert becomes Jewish only after he dips in the Mikvah he cannot say the Beracha before he dips, because he is not yet commanded in the commandments of the Torah. Therefore he says the Beracha after he dips. See Talmud Bavli (Pesachim 7b).
4. The Torah commands all Jews to sit in Sukkot (booths) for seven days on the holiday of Sukkot. See Vayikra 23:42-43.
5. ברוך אתה ה’ אלוהינו מלך העולם שהגיענו לזמן הזה  – Blessed You Hashem, our God, King of the world, Who has brought us to this time. This is a variation of the common Beracha of Shehechiyanu. This Beracha is generally said when a person either has purchased something new, like a new house or new vessels, or when the time has arrived to celebrate a new holiday or to perform a new Mitzvah. In this case the completing building the Sukkah is not a Mitzvah since the real Mitzvah that the Torah commands to perform is to sit in the Sukkah on Sukkot and not to build it. However since the person is excited that he has prepared something in order to perform the actual Mitzvah he says the Beracha of Shehechiyanu to celebrate his excitement. It should be noted that Talmud Yerushalmi (Berachot 9:3, Daf 66a) quotes a different Beraita that says that when a person builds a Sukkah for himself he does not say Shehechiyanu, but rather Asher Kideshanu Bemitzvotav Vetzivanu Laasot Sukkah (Who has sanctifies us with His commandments and has commanded us to make a Sukkah), which implies that according tot hat Beraita building a Sukkah is an actual Mitzvah and that Beracha should be said before he started building the Sukkah, since he is about to begin a new commandment. However from this Tosefta it seems not to be the case and the Tosefta therefore argues on the Yerushalmi regarding which Beracha should be said upon building a Sukkah. For a discussion of the possibilities why building a Sukkah is a Mitzvah or not see the commentary of Rabeinu Manoach on the Rambam (Hilchot Berachot 11:8, Frankel Edition). The custom today, which is not to say a Beracha when making something in order to perform a Mitzvah with it, is based on Talmud Bavli (Menachot 42b) as explained by the Rambam (ibid.) and originates in Babylonia. However it is clear from this Tosefta and Talmud Yerushalmi (Berachot 9:3, Daf 66a) that the original custom in the Land of Israel was to say a Beracha upon preparing the Mitzvah, just it was not clear which Beracha and when it should be said.
6. ברוך אתה ה’ אלוהינו מלך העולם אשר קדשנו במצותיו וצונו לישב בסוכה – Blessed You Hashem, our God, King of the world, Who has sanctified us with His commandments and has commanded us to dwell in the Sukkah.
7. The reason for the opinion of the Tosefta that this Beracha is said only the first time when the person sits in the Sukkah and not anymore is explained by Talmud Bavli (Sukkah 45b). Since the Mitzvah of Sukkah is continuous for seven days, meaning that it applies both during the day and the night, there is never and interruption in the obligation of its performance and therefore a new Beracha is not required. This is in opposition to the Mitzvah of Lulav (see next Tosefta) which is applicable only by day, and therefore since it is interrupted by the night every day it requires a new Beracha every day. It should be pointed out that the matter of the Beracha of Leishev Basukkah being said only once or every time the person enters the Sukkah is disputed by both Tannaim and Amoraim in Talmud Bavli (Sukkah 45b-46a). This Tosefta follows the opinion of the Rabanan quoted in Talmud Bavli, however the custom today follows the opinion of Rebbi since most Amoraim hold like him and therefore we say the Beracha upon entering the Sukkah every time that we enter it.