A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
neh 8:1RELIGIOUS MANNER OF READING AND HEARING THE LAW. (Neh 8:1-8)
all the people gathered themselves together as one man--The occasion was the celebration of the feast of the seventh month (Neh 7:73). The beginning of every month was ushered in as a sacred festival; but this, the commencement of the seventh month, was kept with distinguished honor as "the feast of trumpets," which extended over two days. It was the first day of the seventh ecclesiastical year, and the new year's day of the Jewish civil year, on which account it was held as "a great day." The place where the general concourse of people was held was "at the water gate," on the south rampart. Through that gate the Nethinims or Gibeonites brought water into the temple, and there was a spacious area in front of it.
they spake unto Ezra the scribe to bring the book of the law of Moses--He had come to Jerusalem twelve or thirteen years previous to Nehemiah. He either remained there or had returned to Babylon in obedience to the royal order, and for the discharge of important duties. He had returned along with Nehemiah, but in a subordinate capacity. From the time of Nehemiah's appointment to the dignity of tirshatha, Ezra had retired into private life. Although cordially and zealously co-operating with the former patriot in his important measures of reform, the pious priest had devoted his time and attention principally toward producing a complete edition of the canonical Scriptures. The public reading of the Scriptures was required by the law to be made every seventh year; but during the long period of the captivity this excellent practice, with many others, had fallen into neglect, till revived, on this occasion. That there was a strong and general desire among the returned exiles in Jerusalem to hear the word of God read to them indicates a greatly improved tone of religious feeling.
neh 8:4Ezra . . . stood upon a pulpit of wood--Not made in the form known to us, but only a raised scaffold or platform, broad enough to allow fourteen persons to stand with ease upon it. Ezra's duty was very laborious, as he continued reading aloud from morning until midday, but his labor was lightened by the aid of the other priests present. Their presence was of importance, partly to show their cordial agreement with Ezra's declaration of divine truth; and partly to take their share with him in the important duty of publicly reading and expounding the Scripture.
neh 8:5when 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."
neh 8:7caused the people to understand the law . . . gave the sense--Commentators are divided in opinion as to the import of this statement. Some think that Ezra read the law in pure Hebrew, while the Levites, who assisted him, translated it sentence by sentence into Chaldee, the vernacular dialect which the exiles spoke in Babylon. Others maintain that the duty of these Levites consisted in explaining to the people, many of whom had become very ignorant, what Ezra had read.
neh 8:9THE PEOPLE COMFORTED. (Neh 8:9-15)
This day is holy unto the Lord . . . mourn not, nor weep--A deep sense of their national sins, impressively brought to their remembrance by the reading of the law and its denunciations, affected the hearts of the people with penitential sorrow. But notwithstanding the painful remembrances of their national sins which the reading of the law awakened, the people were exhorted to cherish the feelings of joy and thankfulness associated with a sacred festival (see on Lev 23:24). By sending portions of it to their poorer brethren (Deu 16:11, Deu 16:14; Est 9:19), they would also enable them to participate in the public rejoicings.
neh 8:16THEY KEEP THE FEAST OF TABERNACLES. (Neh 8:16-18)
the people went forth, and brought . . . and made themselves booths, &c.--(See on Lev 23:34; Deu 16:13).
neh 8:17since the days of Jeshua . . . had not the children of Israel done so--This national feast had not been neglected for so protracted a period. Besides that it is impossible that such a flagrant disregard of the law could have been tolerated by Samuel, David, and other pious rulers, its observance is sufficiently indicated (Kg1 8:2, Kg1 8:65; Ch2 7:9) and expressly recorded (Ezr 3:4). But the meaning is, that the popular feelings had never been raised to such a height of enthusiastic joy since the time of their entrance into Canaan, as now on their return after a long and painful captivity.
neh 8:18Also day by day . . . he read in the book of the law of God--This was more than was enjoined (Deu 31:10-12), and arose from the exuberant zeal of the time.
on the eighth day was a solemn assembly--This was the last and great day of the feast (see on Num 29:35). In later times, other ceremonies which increased the rejoicing were added (Joh 7:37).