Musar к Шмот 33:4

ויתאבלו ולא שתו איש עדיו עליו. The fact that the Israelites took off their jewelry while in morning teaches all of us that at a time when we contemplate our general conduct and examine our sins we should go into mourning, cry, sit on the ground, and in exchange for sackcloth remove costly garments, all in sorrow for having killed our soul through sin. Perhaps this will cause G–d to have pity on us.