John Gills Exposition of the Bible Commentary - Psalms 81:3
Blow up the trumpet in the new moon ,.... Either in every new moon, or first day of the month, which was religiously observed by the Jews, 2 Kings 4:23 or rather the new moon, or first day of the seventh month, the month Tisri, which day was a memorial of blowing of trumpets, Leviticus 23:34 , and so the Targum, "blow the trumpet in the month of Tisri,' when their new year began, and was typical of the year of the redeemed of the Lord, of the acceptable year of our God, of the famous... read more
Matthew Henry's Complete Commentary - Psalms 81:1-7
When the people of God were gathered together in the solemn day, the day of the feast of the Lord, they must be told that they had business to do, for we do not go to church to sleep nor to be idle; no, there is that which the duty of every day requires, work of the day, which is to be done in its day. And here, I. The worshippers of God are excited to their work, and are taught, by singing this psalm, to stir up both themselves and one another to it, Ps. 81:1-3. Our errand is, to give unto... read more