Reason why a menstruating woman should use a piece of cloth perfumed with musk after doing ghusl

Al-Bukhaari (314) and Muslim (332) narrated from ‘Aa’ishah
(may Allaah be pleased with her) that Asma’ asked the Prophet (peace
and blessings of Allaah be upon him) about ghusl following menses. He said:
“Let one of you take her water and lotus leaves and clean herself well, then
let her pour water over her head and rub it vigorously so that it will reach
the roots of her hair. Then let her pour the water over herself, then take a
piece of cloth scented with musk and purify herself.” Asma’ said: How should
she purify herself? He said: “Subhaan-Allaah! Purify yourself with it.”
‘Aa’ishah said – as if she whispered it to her – Follow the traces of
blood. 

The reason for using this is to perfume the site and ward off
unpleasant odours. 

Al-Nawawi (may Allaah have mercy on him) said in Sharh
Muslim: The scholars differed concerning the reason for using musk. The
correct view is that of the majority of our companions and others, which is
that the purpose of using musk is to perfume the site and ward off
unpleasant odours. … She should use it after ghusl. If no musk is available,
she should use whatever perfume she can find. If she cannot find any perfume
then it is mustahabb for her to use whatever will remove the odour [soap,
nowadays]. If she cannot find anything, then water is sufficient for her,
but if she fails to perfume it when perfume is available, that is makrooh.
If she is not able to do it then it is not makrooh in her case. End quote. 

Dr. Aaminah ‘Ali Naasir Siddeeq, professor of microbiology in
the College of Science in Jeddah has discovered that musk is a natural
antibiotic for treating skin diseases and genital diseases in humans and
animals. This discovery was patented in the King ‘Abd al-‘Azeez City for
Science and Technology in Riyadh. 

See al-Mujtama’
magazine:

http://www.almujtamaa-mag.com/Detail.asp?InSectionID=81&InNewsItemID=217507

[Article is in Arabic] 

The researcher also presented to the Eighth International
Conference on scientific miracles in the Qur’aan and Sunnah, held in Kuwait
in 1427 AH a paper entitled: Aspects of the scientific miracles of using
musk as an antibiotic against funguses and yeasts that cause disease in
humans, animals and plants.. 

She explained that disease-causing bacteria increase in
number during the menstrual period and that musk has a strong effect in
killing off these harmful microbes. 

See the paper [in Arabic] at: 

http://www.nooran.org/con8/Research/436.pdf

http://www.tafsir.org/vb/archive/index.php?t-6980.html
 

 It is clear that the reason for the menstruating woman using
musk is to perfume the site, to ward off unpleasant odours, and to kill off
disease-causing funguses and yeasts. 

And Allaah knows best.