Albert Barnes Commentary Nehemiah 9:1

"Now in the twenty and fourth day of this month the children of Israel were assembled with fasting, and with sackcloth, and earth upon them." — Nehemiah 9:1 (ASV)

The festival lasted from the 15th day of the 7th month to the first. The 22nd day was a day of solemn observance (Nehemiah 8:18). One day seems to have been allowed the people for rest; and then the work of repentance, for which they had shown themselves ready (Nehemiah 8:9), was taken in hand, and a general fast was proclaimed.