John Gill 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)

Now in the twenty fourth day of this month

The seventh month, the month Tisri or September, two days after the feast of tabernacles was ended:

the children of Israel were assembled with fasting, and with
sackclothes, and earth upon them ;

which were all outward tokens of mourning and humiliation, see (Joel 1:8Joel 1:14) (1 Samuel 4:12) which they could not show during the festival; but that being over, they return to it, see (Nehemiah 8:9) .