I am French and I recently embraced Islam. My question is about the prayer. I would like to know if one men is entitled to direct a prayer meanwhile there is only one woman behind him. In this case, the man and the woman are not married. So, I am wondering if this kind of prayer can be considered like a prayer in group (with more reward). Or, on the contrary is it disadviced or absolutely forbidden ?.


Praise be to Allaah.
 

If this woman is one of his mahrams, there is nothing wrong
with him leading her in prayer and it will be counted as prayer in
congregation. But if she is a non-mahram, and if his leading her in prayer
means that he will be alone with her, then in this case his leading her in
prayer is haraam. 

Al-Nawawi said: 

It says in al-Muhadhdhab: It is makrooh for a man to
lead a non-mahram woman in prayer, because it was narrated that the Prophet
(peace and blessings of Allaah be upon him) said: “No man is alone with
a non-mahram woman but the Shaytaan is the third one present.” 

Al-Nawawi said in his commentary: 

What is meant by it being makrooh is that it is haraam. This
applies if he is alone with her. 

Our companions said: If a man leads his wife or a woman who
is his mahram in prayer, and is alone with her, that is permissible and is
not makrooh, because it is permissible for him to be alone with her in
situations other than prayer. If he leads a non-mahram woman in prayer and
is alone with her, that is haraam for him and for her, because of the saheeh
ahaadeeth that I will quote below, in sha Allaah. 

If he leads (a number of) non-mahram woman in prayer and is
alone with them, the majority of scholars said that this is permissible, and
this was narrated by al-Raafa’i in Kitaab al-‘Adad from our
companions. 

His evidence is the hadeeth which we will quote below, in sha
Allah, and because when there are a number of women together, a man cannot
usually behave inappropriately one of them in the presence of the others.  

With regard to the ahaadeeth mentioned above, one of them is
the report narrated from ‘Uqbah ibn ‘Aamir (may Allaah be pleased with him),
that the Messenger of Allaah (peace and blessings of Allaah be upon
him) said: “Beware of entering upon women.” A man from among the Ansaar
said: “O Messenger of Allaah, what do you think about the in-law?” He said:
The in-law is death.” Narrated by al-Bukhaari and Muslim. The “in-law”
refers to the husband’s relatives; what is meant here is a relative who is
not her mahram, such as the husband’s brother, paternal uncle, cousin,
maternal uncle, etc. The husband’s father, son and grandfather are mahrams
and it is permissible for them to be alone with his wife, even though they
are also in-laws. 

It was narrated from Ibn ‘Abbaas (may Allaah be pleased with
him) that the Messenger of Allaah (peace and blessings of Allaah be
upon him) said: “No one of you should be alone with a woman unless a mahram
is present.” Narrated by al-Bukhaari and Muslim. 

It was narrated from Ibn ‘Amr ibn al-‘Aas (may Allaah be
pleased with him) that the Messenger of Allaah (peace and blessings of
Allaah be upon him) said from the pulpit: “After this day, no man should
enter in secret upon a woman whose husband is absent unless there is another
man or two with him.” Narrated by Muslim.  

What is meant by a woman whose husband is absent means one
whose husband is not in the house, even if he is in the same town.
Al-Majmoo’
, 4/173, 174. 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said: 

The phrase “leading a non-mahram woman or women in prayer who
have no man with them” means: it is makrooh to lead a non-mahram woman or
women in prayer.  

What the author says requires further explanation: 

If there is one non-mahram woman on her own, then to say that
it is only makrooh requires further explanation, if that means being alone
with her. Hence it was interpreted in al-Rawd as meaning that the
Prophet (peace and blessings of Allaah be upon him) forbade a man to be
alone with a non-mahram woman. But we say: If he is alone with her then it
is haraam for him to lead her in prayer, because that which may lead to
something haraam is also haraam.  

If there is more than one woman, i.e., if he leads two women
in prayer, this is also subject to further discussion as to whether it is
makrooh, because if there is a second woman along with the first, this means
that khulwah (being alone with a non-mahram member of the opposite sex) is
no longer an issue, and if the man is trustworthy there is nothing wrong
with him leading the two women in prayer. This happens sometimes in some
mosques where the congregation is small, especially with regard to qiyaam
al-layl in Ramadaan, when a man comes to the mosque and finds no men there,
but he does find two or three or four women in the back of the mosque.
According to what this author is saying, it is makrooh for him to lead these
two or three or four women in prayer. 

But the correct view is that this is not makrooh, and that if
he leads two or more women in prayer, there is no khulwah and it is not
makrooh, unless he is afraid of fitnah (temptation). If he is afraid of
fitnah, then it is haraam, because whatever is a means that may lead to
something haraam is also haraam. 

From the phrase “if there
is no man with them” we may understand that if there is a man with them,
then it is not makrooh, this is clear.  

Al-Sharh al-Mumti’, 4/250-252. 

And Allaah knows best.