Somebody may already have answered your query, but just in case, here is one verse (there are several):
Proverbs 24:17 (NIV) Do not gloat when your enemy falls; when he stumbles, do not let your heart rejoice...
The Song of Miriam
"Then Miriam the prophetess, the sister of Aaron, took the timbrel in her hand; and all the women went out after her with timbrels and with dances. And Miriam answered them:
"Sing to the LORD
For He has triumphed gloriously!
The horse and the rider
He has thrown into the sea!"
Exodus 15:20 (See verses 1-18 for the long version called the Song of Moses)
IMO, sounds like big time rejoicing to me. And if that doesn't prove there is gloating and rejoicing over one's enemies in the Old and New Testament then I can quote many more sections of the Bible as verifiable references. Therefore, the Bible does not clearly exhort against rejoicing over your enemies -- specifically evil enemies.
" ... for he who is hanged is accursed of God ..." Deuteronomy 21:23b
Saddam and muslims understand the deep symbolism of hanging. This will be a long-remembered mark in Iraqi history and another lovely notch in the Hussein family's long belt of insanity.