Matthew Poole and continuators on Leviticus 23:24

24 Speak unto the children of Israel, saying, in the seventh month, in the first day of the month, shall ye have a sabbath, a memorial of blowing of trumpets , an holy convocation.

(i. e.) Solemnized with the blowing of trumpets by the Priests, not in a common way, as they did every first day of every moneth, Numb. 10. 10. but in an extraordinary manner, not onely in Ierusalem, but in all the Cities of Israel. This seems to have been instituted, 1. To solemnize the beginning of the new year, whereof as to civil matters, and particularly as to the Jubilee, this was the first day; concerning which it was fit the people should be admonished, both to excite their thankfulness for Gods blessings in the last year, and to direct them in the management of their civil affairs. 2. To put a special honour upon this moneth. For as the seventh day was the Sabbath, and the seventh year was a Sabbatical year, so God would have the seventh moneth to be a kind of Sabbatical moneth, for the many Sabbaths and solemn feasts which were observed in this more than in any other moneth. And by this sounding of the trumpets in its beginning God would quicken and prepare them for the following Sabbaths, as well that of atonement and humiliation for their sins, as those of thanksgiving for Gods mercies.

Marginal references: Numb. 29. 1.