Orshalom b'SHEM Yah'shua HaMashiach Adonai
NAU Exodus 19:16 So it came about on the third day,
when it was morning, that there were thunder and lightning flashes and a
thick cloud upon the mountain and a very loud trumpet sound, so that all
the people who were in the camp trembled.
Recall from Hebrews that Moses constructed the religious worship of Israel from all he had seen on the mountain (Heb. 8:4,5). He was given a glimpse into heaven. From that glimpse he constructed a worship pattern that was intended to point the people of the older covenant to the Messiah who was to come.
The holy days and all their rituals and instruments were merely types of the person and work of Jesus Christ. In them they would see their need for redemption and the Messiah who would accomplish that redemption for His people. When the Messiah would come they would be able to recognize Him because of all that had witnessed in the old covenant typology.
Of course once He had appeared and accomplished our salvation, a return to old covenant rituals was no longer necessary or desirable. That is why we are told that the old covenant was decaying and about to fade away even in the 1st century (Heb. 8:13). The last vestiges of that (temporary) old covenant were brought to an end when the temple in earthly Jerusalem was destroyed once for all time in AD70. We now worship in the new Jerusalem in Spirit and truth, not being confined to any geographic location or bound by temporary, cultic rituals.