Siman 96

(16.) He told during the days of Elul that he had dreamed that he was walking into a house to hear the voice of the shofar, and he passed before a certain house and heard that they were singing and clapping hand upon hand and dancing greatly, and rejoicing with leaps and great dances in the manner of those who rejoice and laugh greatly. I answered and said: Certainly it is good to enter here to hear the voice of the shofar! [And the rest I do not remember.] And one answered that it is also hinted at in his book that the commandment of the shofar is the aspect of clapping of hands and dancing — as is cited in the Torah "These are the judgments" in Likutay Moharan, vol. 1, Torah 10, which speaks of clapping of hands and dancing, and which cites there the holy Zohar's statement [Tikkunei Zohar 48a]: "bitru'ah d'ihi rucha isa'var el acher — kefiras" etc. — that through this one merits to clapping of hands and dancing. Which is the aspect of: "and that spirit blows in the six joints of the arms and in the six joints of the legs" — see there the entire Torah. It emerges that it is explained there that teru'ah — the shofar-blast — is the aspect of clapping of hands and dancing. And Rabbainu o.b.m. nodded his head in agreement. Afterwards Hashem put it into my heart that it is hinted at in the verse that the shofar is the aspect of song and joy — for [Psalms 126:2]: "Az yimaleh se'chok piynu — ul'shoneinu rinah" ["Then our mouth was filled with laughter and our tongue with song"] — the initial letters spell shofar. And therefore after the verse [Psalms 89:16]: "Fortunate is the people that knows the teru'ah" etc., it is written: "In Your name they rejoice all day" — and see elsewhere (Likutay Moharan, Torah 175) that the essential weeping must come from within joy, for weeping (bechiyah) is the initial letters of "beshimcha yageeloo kul hayom" — "In Your name they will rejoice all day" — see there.