Leviticus 23:24

A sabbath Solemnized with the blowing of trumpets by the priests, not in a common way, as they did every first day of every month, but in an extraordinary manner, not only in Jerusalem, but in all the cities of Israel. They began to blow at sunrise, and continued blowing till sunset. This seems to have been instituted, 1st, 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 God's blessings in the last year, and to direct them in the management of their civil affairs. 2d, To put a special honour upon this month. For, as the seventh day was the sabbath, and the seventh year was a sabbatical year, so God would have the seventh month to be a kind of sabbatical month, on account of the many sabbaths and solemn feasts which were observed in this, more than in any other month. 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 God's mercies.