And the Lord spake unto Moses,.... At the same time, in a continued discourse, concerning some other days, which were to be observed in a sacred manner:
saying; as follows.

the blowing of trumpets represented the preaching of the gospel, by which men are called to repent of sin, and to accept the salvation of Christ, which was signified by the day of atonement. Also it invited to rejoice in God, and become strangers and pilgrims on earth, which was denoted by the feast of Tabernacles, observed in the same month. At the beginning of the year, they were called by this sound of trumpet to shake off spiritual drowsiness, to search and try their ways, and to amend them. The day of atonement was the ninth day after this; thus they were awakened to prepare for that day, by sincere and serious repentance, that it might indeed be to them a day of atonement. The humbling of our souls for sin, and the making our peace with God, is work that requires the whole man, and the closest application of mind. On that day God spake peace to his people, and to his saints; therefore they must lay aside all their wordly business, that they might the more clearly hear that voice of joy and gladness.

On the first day of the seventh month there was to be shabbathon, rest, i.e., a day of rest (see Exodus 16:23), a memorial of blowing of trumpets, a holy convocation, the suspension of laborious work, and the offering of a firing for Jehovah, which are still more minutely described in the calendar of festal sacrifices in Numbers 29:2-6. תּרוּעה, a joyful noise, from רוּע to make a noise, is used in Leviticus 23:24 for שׁופר תּרוּעה, a blast of trumpets. On this day the shophar was to be blown, a blast of trumpets to be appointed for a memorial before Jehovah (Numbers 10:10), i.e., to call the congregation into remembrance before Jehovah, that He might turn towards it His favour and grace (see at Exodus 28:12, Exodus 28:29; Exodus 30:16); and from this the feast-day is called the day of the trumpet-blast (Numbers 19:1). Shophar, a trumpet, was a large horn which produced a dull, far-reaching tone. Buccina pastoralis est et cornu recurvo efficitur, unde et proprie hebraice sophar, graece κερατίνη appellatur (Jerome on Hosea. Leviticus 5:8).
(Note: The word תּרוּעה is also used in Numbers 10:5-6 to denote the blowing with the silver trumpets; but there seems to be no ground for supposing these trumpets to be intended here, not only because of the analogy between the seventh day of the new moon as a jubilee day and the jubilee year (Leviticus 25:9-10), but also because the silver trumpets are assigned to a different purpose in Numbers 10:2-10, and their use is restricted to the blowing at the offering of the burnt-offerings on the feast-days and new moons. To this we have to add the Jewish tradition, which favours with perfect unanimity the practice of blowing with horns (the horns of animals).)
The seventh month of the year, like the seventh day of the week, was consecrated as a Sabbath or sabbatical month, by a holy convocation and the suspension of labour, which were to distinguish the first day of the seventh month from the beginning of the other months or the other new moon days throughout the year. For the whole month was sanctified in the first day, as the beginning or head of the month; and by the sabbatical observance of the commencement, the whole course of the month was raised to a Sabbath. This was enjoined, not merely because it was the seventh month, but because the seventh month was to secure to the congregation the complete atonement for all its sins, and the wiping away of all the uncleannesses which separated it from its God, viz., on the day of atonement, which fell within this month, and to bring it a foretaste of the blessedness of life in fellowship with the Lord, viz., in the feast of Tabernacles, which commenced five days afterwards. This significant character of the seventh month was indicated by the trumpet-blast, by which the congregation presented the memorial of itself loudly and strongly before Jehovah on the first day of the month, that He might bestow upon them the promised blessings of His grace, for the realization of His covenant. The trumpet-blast on this day was a prelude of the trumpet-blast with which the commencement of the year of jubilee was proclaimed to the whole nation, on the day of atonement of every seventh sabbatical year, that great year of grace under the old covenant (Leviticus 25:9); just as the seventh month in general formed the link between the weekly Sabbath and the sabbatical and jubilee years, and corresponded as a Sabbath month to the year of jubilee rather than the sabbatical year, which had its prelude in the weekly Sabbath-day.