Numbers 29:1

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, ye shall have a holy convocation;
see ( Leviticus 23:24 ) ,

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

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