1)
Why was this on the 24th?
1.
Malbim: The 23rd is Isru Chag (the day after the festival); one may not fast then.
2)
What earth was on them?
1.
Rashi: They put earth on their heads.
Why was this on the 24th?
Malbim: The 23rd is Isru Chag (the day after the festival); one may not fast then.
What earth was on them?
Rashi: They put earth on their heads.