Can you stand for the whole service?

Question

During services, sometimes we sit and sometimes we stand, depending on the prayer. For some prayers we are required to stand: Amidah (as its name implies), Shofar, Bar'chu, Alenu, etc. But are we ever required to sit? Can someone stand for the duration of the service, or would he be breaking some laws?

All I recall is a commentator saying that we sit during Ashrei because it says "Ashrei yoshvei betecha -- Happy are those who dwell in your house". When you are in your house, you relax, sit down and kick up your shoes. But he did not say you HAVE to sit during Ashrei.

Answer 1

The Shulchan Aruch writes "[Tachanun is performed] seated" (OC 131:2). In his Beis Yosef, he explains that “according to the understanding of scholars of Kabbalah” one should be particular to sit during Tachanun.

However, preceding that line in the Beis Yosef, he quotes the Rivash as saying that it doesn’t matter whether one stands or sits. Based on this dispute, the Mishnah Berurah (131:10), quoting “the Acharonim,” rules that in a pressing circumstance, one may rely on the Rivash and say Tachanun standing; for instance, if one finished davening, and the Tzibbur began saying Tachanun before the requisite amount of time before one takes his three steps forward, he should put his head on his arm while still standing. Likewise, if he’s unable to sit because of where the next guy over is still saying Shemoneh Esrei, he should say Tachanun standing.

In summary: According to the Shulchan Aruch, Tachanun should be said seated. According to the Rivash, Tachanun would not answer your question. According to the Mishnah Berurah, Tachanun usually qualifies, but not always.

Answer 2

Rav Shachter quotes Igros Moshe discussing haftorah

"It is not permissible for one to stand for the Keriah in a Shul where the custom is to sit..."

Also, a friend mentioned to me that he davened in a sefardi shul which was stringent to require everyone to sit during krias hatorah. (Perhaps based on the Arizal quoted in the Kaf HaChaim or Rav Ovadia Yosef, but it doesn't sound like either required sitting per se.)

Answer 3

I will only hint at it "Kabbalicly".

1. The Pasuk says "ואתה קדוש יושב תהילות ישראל", Ariz"L learns that our relationships with Hashem are sometimes "give" and sometimes "receive".

2. When we "receive" we sit (or lie) when we "give" we stand (and the other part sits or lies). This applies, for example, to Tahanun of Krishm"A, which is "קבלת עול מלכות שמים".

3. That teachings are "allegorically" manifested in the Teffilah thru the standing and sitting alternations.

It's important to note that all of it is customary and not obligatory, one does not repeat if performed it differently.