Standing for Mizmor Lesoda:[1]

One is required to stand for the recital of Mizmor Lesoda.[2] [Some Poskim[3], however, rule that according to the final ruling of Admur, one is not required to stand. Furthermore, some[4] rule one is specifically to recite Mizmor Lesoda in a sitting position. Practically, the Chabad custom is to stand for its recital, and only sit down afterwards, prior to Yehi Kavod.[5] So is also the widespread Ashkenazi custom, while the Sephardi custom is to sit for its recital.[6]]

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[1] Admur Kama 1:14; Yad Ahron 1 on Hagahos Hatur 51 in name of Mahariy Sarug; Derech Hachaim 30:9; Siddur Beis Oved 3; Siddur Yaavetz; Kitzur SHU”A 14:4; The Mishneh Berurah does not state an opinion on this matter

[2] The reason: The reason why Mizmor Lesoda is to be recited while standing is because it mentions the Todah offering, which is a sacrifice, and is thus similar to the Karbanos which were offered while standing. [Admur ibid]

[3] Piskei Hassidur 10 based on Admur Mahadura Basra 1:9; In accordance, Ketzos Hashulchan 18:4 omits the need to stand by Mizmor Lesoda

Background: Admur in Mahadura Basra 1:9 rules one is not required to recite the Karbanos in a standing position, being that he is not a Kohen which is serving the Karban. Accordingly, the same would apply for Mizmor Lesoda, that it is not necessary to be said standing. [Piskei Hasiddur ibid] However see Likkutei Sichos in next footnote who learns differently.

[4] Shaar Hakavanos p. 50 and Peri Eitz Chaim Shaar Hakarbanos in name of Arizal, brought in Piskei Hasiddur ibid; Shalmei Tzibur p. 68; Kesher Gudal 7:38; Shaarei Teshuvah 51:9; Kaf Hachaim [Falagi] 12:18; Nesiv Hachaim 30:3, in a gloss on the Derech Hachaim, in name of Poskim ibid; Shulchan Hatahor 51:7; Kaf Hachaim 48:1 and 51:48

[5] Likkutei Sichos 12:28 footnote 52 [printed in Shulchan Menachem 1:210] that the ruling of Basra ibid does not conflict the ruling of Kama ibid regarding Mizmor Lesoda; Custom of the Rebbe, and so is the widespread Chabad custom; Custom printed in footnote 65 of new Shulchan Aruch

The reason: Although in Basra ibid Admur rules that one is not required to stand for the Karbanos, Mizmor Lesoda is an exception as a)It was not explicitly mentioned in the Basar and b) It is said mainly as a song of praise, and not as a Karban. [Likkutei Sichos ibid; See Admur 51:1; Beis Yosef 51]

[6] Piskeiy Teshuvos 51:21