John Gill Commentary Ezra 10:4

"Arise; for the matter belongeth unto thee, and we are with thee: be of good courage, and do it." — Ezra 10:4 (ASV)

Arise
From the ground, where he lay prostrate:

for this matter belongs to you ;
as a priest and scribe of the law, well versed in it, and therefore could direct what was to be done according to it; and as a ruler under the king of Persia, and a commissioner of his, to inquire whether the law of God was observed by the Jews, (Ezra 7:14) and so had authority to put the law in execution:

we also will be with you ;
to help and assist in the reformation of this evil:

be of good courage, and do it ;
do not despair of going through it, though there may be some opposition to it; begin, and doubt not of succeeding.