Why do people stand for Psalm 100?

Question

Partway through the P'sukei d'Zimra section of the morning service is Psalm 100 (Mizmor l'Todah). Many, but not all, people stand for the recitation of this particular psalm. Prayer books vary, either not mentioning standing, saying that some people stand for this one, or like Artscroll, simply say "Psalm 100 is recited while standing".

Why is this psalm different from all other psalms? Where is standing for it mandated? Broadly, who follows it and who doesn't?

I have seen Ashkenazim who do or don't, Sefardim who do or don't (but my sample set of Sefardim is very small), Orthodox who do or don't, Conservative who do or don't. I cannot tell if this breaks down on geographic lines, ideological lines, or just people who don't want to get up for such a short period.

Answer 1

It is a dispute in poskim, and there are different customs about which one to follow.

Why is this psalm different than all other Psalms? Two reasons, one is that it has a reference to the sacrifice, and when a Kohen brought the sacrifices he was standing (that opinion would also hold to stand while saying the Korbanos that preceded Baruch Sheamar). The second reason is that it says in Vayikra Rabba 9:7 that all songs will be nullified in the future except for this one, it is of particular importance (and therefore should be drawn out in a song - O.C. 51:9). That latter reason doesn't necessarily mean to stand, but in any event it references the sacrifice.

Where is standing for it mandated? The Yad Aharon (Rabbi Aahron Alfondari) is the specific source for saying it standing (commentary to O.C. 1) (Quoting the Mahari Saruk - a student of the Arizal). Others argue.

Broadly, who follows and who doesn't? It really doesn't break along neat lines, like Sefardi and Ashkenazi, etc. However, those who say it right after Baruch Sheamar will usually say it standing because they are standing anyway.

Answer 2

Shaarei Teshuvah 51 (9) and Kitzur Shulchan Oruch 14 (4) point out that Mizmor L'Todah is instead of a Korban Todah (thanksgiving offering) and since korbanot were offered standing, one should stand for Mizmor L'Todah. The Ari z”l says one should sit.

See Praying with fire which says

But why do we recite מזמור לתודה every day if it was sung only when a person “miraculously” survived a life-threatening situation? The Siddur She’lah and Ya’avitz explain that no day goes by without man experiencing a “miracle.” However, the recipients of these miracles do not always recognize them (Nidah 31a). Therefore, we recite מזמור לתודה to acknowledge the miracles inherent in every day.