(Mishnah): If one did Kabalah while sitting down, it is Pasul.

19b (Beraisa): The Kohen puts each hand on the corresponding foot, and is Mekadesh (pours water on them);

R. Yosi b'Rebbi Yehudah says, he puts one hand on the other, and puts them on his feet, which were one on the other, and is Mekadesh.

Chachamim: One cannot stand this way!

(Rav Yosef): R. Yosi holds that another Kohen supports him.

(Abaye): R. Yosi and Chachamim argue about whether standing Min ha'Tzad (with support) is considered standing.

Question (Rav Sama brei d'Rav Ashi): Why can't the Kohen sit?

Answer (Ravina): Kidush is called "Leshares"; Avodah must be standing.

Shevuos 30b: Rav Huna's widow came for judgment in front of Rav Nachman. He could not sit, for a Chacham's wife is like a Chacham.

Question: The judge must sit at the time of the final verdict!

Answer: He sat half-way, like one untying his shoe, at the time.

Megilah 21a - Contradiction: It says "va'Eshev (I sat) on the mountain", and it says, "I stood on the mountain"!

Resolution (R. Chanina): Moshe did not sit or stood. He was bent over.

Rosh (Megilah 3:1): One who reads from the Torah must stand. He may not even support himself, like it says in the Yerushalmi.

Tosfos (19b DH Amidah): Chachamim say that Min ha'Tzad is not called standing. It seems that when one reads from the Torah, he may not stand supported, for in Megilah we say that one must stand. Also the Yerushalmi says that just like Torah was given with fear, we must conduct with it with fear.

Tosfos (19b DH v'Leisev): The Gemara did not suggest truly sitting, for one may not sit in the Azarah. Rather, it suggested standing supported.

Rivash (266 DH v'Chen): A case occurred in which a Beis Din accepted testimony while standing, leaning on a pillar. The Acharonim agreed that if they stood, b'Di'eved the testimony is valid. It is only l'Chatchilah that the witnesses and litigants must stand, and the judges must sit. Also, perhaps leaning on a pillar is considered sitting. If he would fall if it were removed, this is not standing. We hold (Zevachim 19b) like the first Tana of R. Yosi b'Rebbi Yehudah that standing Min ha'Tzad, i.e. he cannot stand without support, is not called standing. This is like bowing. It is called sitting, for it is not full standing, and is called standing, for it is not full sitting. All the more so standing supported, which is not standing, is called sitting. Also, the law that judges must sit is only an Asmachta mid'Rabanan. If so, l'Chatchilah one may stand supported.

Shulchan Aruch (CM 17:1): L'Chatchilah, the witnesses always stand.

Rema: For this, standing while supporting himself on something is called standing.

Source (Darchei Moshe 2): The Rivash says so.

SMA (6): The Rivash says that it is called sitting regarding judges. We are lenient about both of these since it is only an Asmachta. However, the judges and witnesses may not stand supported at the same time, for in any case one of them does improperly.

Bach (2): Megilah 21a asked a contradiction, and answered that Moshe bowed. This is called standing and sitting. The same applies to standing with support. This does not suffice for Kohanim who must wash their hands and feet, for the Torah requires "La'amod u'Leshares", i.e. standing without support. Here, one must stand only mid'Rabanan. For this it is called standing, and also sitting, unlike the SMA wrote.

Bach (28:22): Standing with support is called standing and it is called sitting, therefore, it is Kosher for witnesses and for judges. Rav Nachman sat half-way when giving the final verdict for Rav Huna's widow. This was considered standing with respect to her, and it was considered sitting regarding the final verdict.

Taz: I rejected the Bach's proof. Here, we learn from one verse that judges must sit and litigants must stand, and witnesses are no better than litigants, for it is only an Asmachta (Rivash). Surely, Chachamim enacted in one way for witnesses and litigants. Since it says that Moshe sat and the people stood, this implies that they were different. The honor shown to a Chacham (or his wife) is not related to the final verdict (so one does not depend on what fulfills the other). Also, there Rav Nachman had no alternative (how to fulfill both at the same time). The Rema says that this is called standing. I disagree. How did he learn from the Rivash to equate it to bowing? The Rivash said that bowing is called sitting, and all the more so standing supported, which is not standing at all! Also the Beis Yosef brought the Rivash only to teach that it is called sitting. Zevachim 19b says that it is not standing. The Bach answered me that Zevachim 19b discusses Kidush, which requires standing mid'Oraisa. Here, standing supported fulfills standing mid'Rabanan. I say that we cannot distinguish between kinds of standing. We learn standing of witnesses from standing of litigants. If we could distinguish, how could the Rivash learn from standing for Kidush?

Ha'Magiha: The Rema learned from the final words of the Rivash 'also, since the law that judges must sit is only an Asmachta mid'Rabanan. If so, l'Chatchilah one may stand supported.' I.e. even without the above reason, here it is Kosher because it is only mid'Rabanan. Even though it is closer to standing than to sitting, for it is called standing supported, (and it is never called sitting through something else, yet it is valid for what requires sitting. All the more so it is valid for what requires standing!) Even though the Radvaz (1:1142, b'Sof) says that we may not rely on one reason that a Posek writes together with other reasons, here is mid'Rabanan, so we may rely on it.

Magen Avraham (141:2 and 426:11): The Rema saw the Beis Yosef (Sof Siman 28) say in the name of the Rivash that if testimony was accepted standing, b'Di'eved it is Kosher. If they stood supported, it is l'Chatchilah, for this is not sitting. The text should say 'this is like sitting', i.e. for judges. In Shevuos 30b it is also like standing, but there we require only Hidur. When one must stand, one may not stand supported (Tosfos). Perhaps testimony is more lenient, but there is no necessity to say so.

Tumim (2): Indeed, there is no proof from the Rivash. The Magen Avraham says that sitting in the Azarah it is only due to honor of the Shechinah, and it is no disgrace to stand supported. The same applies in Beis Din. Witnesses must stand because they are in front of Hash-m! If standing supported suffices where Kevod Hash-m was openly seen, all the more so it suffices in Beis Din, where we need not show such awe of Hash-m, especially according to the SMA, who says that it a mere Asmachta that witnesses must stand. Chachamim enacted not to judge kings of Yisrael due to a case in which Yanai refused to stand. They did not decree about kings from David, since they may sit in the Mikdash, and all the more so in Beis Din! Why did the Torah need to teach that Avodah must be standing? Kohanim may not sit in the Azarah! Rather, one may stand supported; the verse requires full standing for Avodah. This is why the Ri (Tosfos Sotah 40b Sof DH veha'Amar) asked, if a Kohen Gadol may sit in the Azarah, Zevachim 19b is difficult. The verse obligates even a Kohen Gadol to stand for Avodah, so there is no source to require full standing!

Urim (7): One should be stringent to require witnesses to stand without support, especially if the judges stand supported.

Urim Gedolim (Drush l'Parshas Vayera, cited in R. Akiva Eiger): One must stand for Torah, but a Melech Yisrael may sit (for Hakhel - Sotah 41a). Witnesses and litigants are more stringent; a Melech Yisrael must stand. One may not stand supported when reading the Torah. All the more so it is Pasul for testimony! Moshe bowed while learning from Hash-m. This shows that it is unlike standing supported. The Rivash did not learn from Megilah, for standing supported is unlike bowing.He needed to learn from Zevachim.

Shulchan Aruch (28:26): If testimony was accepted (while the judges were) standing, it was valid. If they were leaning on a beam, it is permitted even l'Chatchilah, for standing supported is like sitting.