From the early Church Fathers to now.
1 Jewish · 2 Reformed · 1 Methodist · 1 Catholic
“And Esdras opened the book before all the people: for he was above all the people: and when he had opened it, all the people stood.”
“for he was above all the people Therefore, they all saw him. and when he opened it, all the people stood And when he opened it to read, all the people stood silent. stood Heb. עָמְדוּ, an expression of silence (they stood silent), like (Job 32:16): “...for they remained silent (עָמְדוּ) ; they no longer answered.””
“And Ezra opened the book in the sight of all the people (for he was above all the people),.... So plainly seen by them, and what he did, and the more easily heard, for which purpose the pulpit was made for him to stand in: and, when he opened it, all the people stood up; that they might the better hear the law read, as well as in honour and reverence of it; the Jews say (m), that from the times of Moses to Rabban Gamaliel, they learned the law only standing; but after his death a disease came into the world, and they learned it sitting; and now it is a canon with them, that it is not necessary to stand at the reading of the law (n). (m) T. Bab. Megillah, fol. 21. 1. (n) Schulchan Aruch, par. 1. Orach Chayim, c. 146. sect. 4.”
“All the people stood up - This was out of respect to the sacred word: in imitation of this, when the gospel for the day is read in our churches, all the people stand up.”
“Stood, out of respect, as we do while the gospel is read. See Numbers xxiii. 18. (Calmet)”
“when he opened it, all the people stood up--This attitude they assumed either from respect to God's word, or, rather, because the reading was prefaced by a solemn prayer, which was concluded by a general expression of "Amen, Amen."”
The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.