Ruling on women parting their hair and wearing it in a bun
Question

What is the ruling on styling the hair for wedding parties, i.e., wearing the hair up? And what is the ruling on that for the bride? Because usually brides style their hair for the wedding night?.
Praise be to Allah.There is nothing wrong with a woman styling her hair and adorning it for the wedding night, rather that is something that is good and desirable. And there is nothing wrong with helping her to do that, on condition that this does not involve imitating the kaafir women or immoral women. What is meant by imitating them is styling the hair in manners that are known to be unique to the kaafir woman, or is known to be a style of a certain kaafir or immoral woman. That is because the Prophet (peace and blessings of Allaah be upon him) said: “Whoever imitates a people is one of them.” Narrated by Abu Dawood, 4031; classed as saheeh by al-Albaani in Saheeh al-Jaami’ al-Sagheer. We have already mentioned the definition of the kind of imitation that is forbidden in the answer to question no. 32533. 
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked about adopting hairstyles from fashion models – is that included in the hadeeth of the Prophet (peace and blessings of Allaah be upon him), “Whoever imitates a people is one of them”? He replied: “The same applies to hair: it is not permissible for a woman to style her hair in the manner of kaafir and immoral women, because whoever imitates a people is one of them. 
I would like to take this opportunity to advise the Muslim woman and those who are in charge of them to avoid these (fashion) magazines and these styles which encourage imitation of the ways of the kuffaar and liking the indecent clothes that they wear, that have nothing whatsoever to do with the modesty of Islam, and these fashions regarding hair styles. The Muslims should be distinct from others as dictated by Islamic sharee’ah and the Islamic attitude, so that the Muslim ummah may regain its pride and honour.  
From Majmoo’ Fataawa al-Shaykh Ibn ‘Uthaymeen, p. 12, question no. 188 
With regard to wearing the hair up, or making it into a bun on top of the head, or parting it at the side, some scholars disallow this, lest it be an imitation of the kaafir women. Some of them included the bun in the condemnation narrated from the Prophet (peace and blessings of Allaah be upon him): “There are two types of the people of Hell whom I have not yet seen: people with whips like the tails of cattle with which they strike the people, and women who are clothed yet naked, astray and leading others astray, with their heads like the humps of camels, leaning to one side. They will not enter Paradise nor even smell its fragrance, although it fragrance may be detected from such and such a distance.”  Narrated by Muslim, 2128. 
If we look at the parting of the hair on one side, for example, this may have been a fashion that was unique to kaafir and immoral women at one time, then it stopped being unique to them and spread to the Muslim women, and no one would think that the one who does it is a kaafir or an immoral woman. In that case the ruling on imitating the kuffaar no longer applies, so it is not haraam. 
Al-Haafiz said in al-Fath (1/307), when discussing the mayaasir al-arjawaan, which is a kind of small cushion which a horse-rider places beneath him, which was something that the Persians used to do: If we say that this is forbidden because it is an imitation of the Persians, then the prohibition is for a religious reason, but that was one of their unique features at that time, when they were kaafirs, but because it is no longer one of their unique features, the reason for disallowing it no longer applies, so it is no longer makrooh. And Allaah knows best. 
He also said, refuting those who regarded wearing the taylasaan (pallium, a large rectangular cloak as worn by the ancient Greeks) as a kind of imitation of the kuffaar, because it is the clothing of the Jews as mentioned in the hadeeth about the Dajjaal: It is appropriate to quote the hadeeth about the Jews at the time when the taylasaan is one of their unique features, but this does not apply at the present time, so now it is included among that which is permissible. 
Fath al-Baari, 10/274. 
We have also quoted other material form him which supports this view, in the answer given above. And Allaah knows best. 
This is the fatwa of the scholars with regard to women wearing the hair in a bun and parting the hair on the side. 
It says in Fataawa al-Lajnah al-Daa’imah (17/126): 
What is the ruling on a woman parting the hair on the side, and making only one braid, and making it into a bun, with the intention of making herself beautiful for her husband or to look good because it suits her? 
With regard to parting the hair on the side, this involves imitating the kaafir women, and it is proven that the Messenger of Allaah (peace and blessings of Allaah be upon him) said it is haraam to imitate the kuffaar. 
With regard to gathering the hair into and letting it hang down the back, either braided or not braided, there is nothing wrong with that so long as it is covered (hijab). But making it into a bun (on top of the head) is not permitted, because that is an imitation of kaafir women and it is haraam to imitate them. The Prophet (peace and blessings of Allaah be upon him) warned against that when he said: “There are two types of the people of Hell whom I have not yet seen: people with whips like the tails of cattle with which they strike the people, and women who are clothed yet naked, astray and leading others astray, with their heads like the humps of camels, leaning to one side. They will not enter Paradise nor even smell its fragrance, although it fragrance may be detected from such and such a distance.”  Narrated by Ahmad and Muslim. 
Shaykh Fawzaan was asked: What is the ruling on parting the hair on the side and not in the middle? He replied: It is not permissible for a woman to part her hair on the side. Shaykh Muhammad Ibraaheem (may Allaah have mercy on him) said: “With regard to what some Muslim women do nowadays, parting the hair on the side and gathering it on top of the head, or doing the parting like European women, this is not permissible, because it involves imitating the kaafir women. From Majmoo’ Fataawa al-Shaykh Muhammad ibn Ibraaheem, 1/47. 
Al-Muntaqa, 3/321 
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked: What is the ruling on a woman gathering her hair on top of her head? 
If the hair is gathered on top of the head, this is regarded by the scholars as being included in the prohibition or warning that was narrated from the Prophet (peace and blessings of Allaah be upon him) in his hadeeth: “There are two types of the people of Hell whom I have not yet seen: …  and women who are clothed yet naked, astray and leading others astray, with their heads like the humps of camels, leaning to one side.” So if the hair is on top of the head, it is not allowed. But if it is at the nape of the neck, for example, then there is nothing wrong with it, unless the woman is going out to the marketplace, in which case this is a kind of tabarruj because it can be noticed through the abayah, so this comes under the heading of tabarruj and is a means of fitnah, so it is not allowed.
From Fataawa al-Mar’ah, Jam’ al-Musnad, p. 218.