The riddle was originally in Arabic and was then translated into English.
Due to the many Arabic variations of it as well as differences that have come about due to translation, it is meaningless in English.
When translated properly, it goes something like this:
A 5 letter word, mentioned once in the Quran, beginning with "mim".
It is whiter than ice (or brighter than the Sun) and darker than night.
Men use it thrice a day, while women only use it once in a lifetime.
It is haram to eat, yet halal to drink.
The answer is Maqabir (Graveyards).
Mentioned in surah "Takarthur" ie. "Hata Zurtum al-Maqabir"
made up of 5 letters begins with "mim"
If a persons actions are good it is brighter than the sun in the grave, while for an evil-doer it is darker than night.
If the "whiter than ice" version is taken is could mean that the kafan is whiter than ice, then the grave is darker than night.
Men visit it three times a day (ie. they bury the dead in it during three times viz. the periods between the three forbidden times) while women only visit the graveyard when they pass away.
The meat of the dead cannot be consumed ie. backbiting him is forbidden.
The part about drinking being halal doesn't seen to have been solved. People have mentioned different interpretations, yet all seem farfetched.