Albert Barnes Commentary Ezra 3:1

"And when the seventh month was come, and the children of Israel were in the cities, the people gathered themselves together as one man to Jerusalem." — Ezra 3:1 (ASV)

The seventh month - i. e., the month Tisri (nearly our September), the most sacred month in the Jewish year (Exodus 23:16; Leviticus 23:24–41).