are You, Lord, Who feeds all"). the blessing forms part of a series (, "a blessing that is next to another") and the opening formula is omitted, except in the first benediction of each series, and only the conclusion is phrased in the style of a long blessing. The second section of the Birkat Hamazon, for instance, begins with the words (, "We thank You"), and ends with the blessing ("Blessed are You Lord, for the land and the food"). Safek berakhah In certain cases it is doubtful whether a blessing should be said. For example, when someone doesn't remember whether he has already recited the proper blessing or not. One cannot argue to recite the blessing "just to be sure", because it is forbidden to say a "" (an unnecessary blessing) so as not to transgress the grave prohibition of taking God's name in vain. The ruling in such cases is to say the blessing in a D'Oraita case, and to not say it in a D'Rabbanan case. Reciting amen The most common context in which an amen is required by halakhah is after one hears a blessing recited. In fact, it is prohibited to willfully refrain from responding amen when it is indicated. The source of this requirement is the verse in Deuteronomy 32:3: "When I proclaim the name of Hashem, give glory to our God." This mandate refers to the mention of the Tetragrammaton, which was only pronounced at certain specific times within the confines of the Holy Temple in Jerusalem. Whoever heard this special name of God mentioned was obliged to respond with Barukh shem kvod malkhuto l'olam va'ed (, "Blessed be the Name of His glorious kingdom for all eternity"). With the destruction of the Temple in 70 CE, however, pronouncing the Tetragrammaton was prohibited, and was replaced with the pronunciation Adonai. Although this term bears significant holiness (and is in fact one of the seven names of God) and may not be pronounced without purpose, it may be pronounced when appropriate in prayer and blessings. The aforementioned response for the Tetragrammaton, however, is not warranted when one hears Adonai pronounced. The Talmudic Sages therefore mandated that one must answer amen at the completion of a blessing outside of the Temple, comparable to the barukh shem that was used in the Holy Temple. However, while "barukh shem is an expression of praise and honour, amen