Answer
Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In in this fatwa:
It is permissible to delay ghusl (ritual bath) until the time of Fajr, but it is recommended for the husband and wife to perform wudu (ablution) before they sleep.
Responding to the question, Sheikh M. S. Al-Munajjid, a prominent Saudi Muslim lecturer and author, states:
Islam is the religion of cleanliness. Allah Almighty says, “Truly Allah loves those who turn unto Him, and loves those who have a care for cleanness.” (Al-Baqarah 2:222) The Prophet (peace and blessings be upon him) is reported to have said,“Cleanliness is half of faith.”
It is permissible to delay ghusl (ritual bath) until the time of Fajr, but it is recommended for the husband and wife to perform wudu (ablution) before they sleep. This was the view of the majority of scholars, and An-Nawawi reported that there was scholarly consensus on this point. (Al-Kafi, 1:173; Al-Muhadhdhab, 1:33; Al-Mughni, 1:229)
Their evidence is the hadith of Aishah (may Allah be pleased with her), whose authenticity is agreed upon. She narrated that when the Messenger of Allah (peace and blessings be upon him) wanted to sleep whilst he was in a state of impurity (janabah), he would wash his private parts and perform ablution as for Prayer.
They also use as evidence the report narrated by Ibn `Umar (may Allah be pleased with him) who said that `Umar said, “O Messenger of Allah, may anyone of us sleep when he is in a state of impurity?” He said, “Yes, if he performs ablution.” (Al-Bukhari and Muslim)
The wisdom behind performing ablution is that it reduces the impurity and is better for the body.
The followers of the Zhahiri school of thought and Ibn Habib among the Malikis thought that it was obligatory for the person who is in a state of impurity to performwudu’, on the basis of the hadith of `Umar referred to above.
Allah Almighty knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.
Source: Excerpted, with slight modification, from: www.islamqa.info/en