Also in the day of your gladness
When they should return from the enemy's country conquerors, or have vanquished the enemy that came against them into their own land, and so would fix a day of rejoicing, like the days of Purim, and the seven days when Hezekiah rejoiced, as Aben Ezra observes; and so any time of rejoicing on account of any extraordinary deliverance and salvation:
and in your solemn days;
or festivals, as the passover, pentecost, and tabernacles, which were proclaimed by sound of trumpet, ( Leviticus 23:2 ) ;
and in the beginnings of your months;
their new moons, especially on the first day of the seventh month, which was a feast of blowing of trumpets, ( Leviticus 23:24 ) ;
ye shall blow with the trumpets over your burnt offerings, and over
your peace offerings;
expressing joy for the acceptance of them, and especially when they had, by faith, a view of the great sacrifice of Christ typified by them: this is a fourth use of the trumpets, and may denote the spiritual joy had by believers, through the ministration of the Gospel, and ordinances of it on the Lord's day, and other seasons, and particularly at the feast of the Lord's supper, in the view of peace and reconciliation, and atonement made by the sacrifice of Christ:
that they may be to you for a memorial before your God;
as it were, to put him in mind of the promises he has made, and the blessings he has laid up as a covenant God for his people:
I [am] the Lord your God;
who had a right to appoint such things to be observed by them, and by whom, as their covenant God, they were laid under obligation to regard them.
The Brenton translation of the Septuagint is in the public domain.