In the book of Nehemiah (chapter 8), we find a description of an ancient Rosh HaShanah at the time of rebuilding Israel after a period of exile.
“When the seventh month arrived – the Israelites being settled in their towns – the entire people assembled as one man in the square (in Jerusalem) before the Water Gate, and they asked Ezra the scribe to bring the scroll of Moses .. On the first day of the seventh month (Rosh HaShanah) Ezra the priest brought the teaching before the congregation, men and women and all who could listen with understanding…”
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“Nehemiah….Ezra… and the Levites….said to the people” This day is holy to the Lord your God; you must not mourn or weep” …”Go, eat choice foods and drink sweet drinks and send portions to whoever has nothing prepared, for the day is holy to our Lord….Then all the people went to eat and drink and send portions and make great merriment, for they understood the things they were told.”