John Gill Commentary Numbers 29:1

"And in the seventh month, on the first day of the month, ye shall have a holy convocation; ye shall do no servile work: it is a day of blowing of trumpets unto you." — Numbers 29:1 (ASV)

And in the seventh month The month Tisri, as the Targum of Jonathan, which answers to part of our September and October; a month famous for days to be religiously observed, having more of them in it than any other month in the year:

on the first day of the month, you shall have a holy convocation ; see (Leviticus 23:24) ,

you shall do no servile work ; therefore, in the place referred to, is called a sabbath:

it is a day of blowing the trumpets to you ; of which, (See Gill on Leviticus 23:24).