A hijab (Arabic: حجاب ḥijāb) in common English usage is a veil worn by some Muslim women in the presence of any male outside of their immediate family, which usually covers the head and chest. The term can refer to any head, face, or body covering worn by Muslim women that conforms to Islamic standards of modesty. Hijab can also refer to the seclusion of women from men in the public sphere, or it may denote a metaphysical dimension, for example referring to "the veil which separates man or the world from God." People usually talk about "the hijab" rather than "a hijab", as evidenced by this article.
Dress of the female must have all conditions of full Hijab including avoiding tight cloth and transparent cloth. Color of the outer dress should not be attractive to men.
Real Hijab requires the woman to cover her hair and body with out showing its shape. Wearing her hair in bun goes against this condition of Hijab.
Permissibility presupposes possibility, and it is generally not possible to force someone in their late teens or beyond to do something, except when they are physically in your presence.
Assuming your daughter has her own life outside the home (for instance, attending school or university, a job, socializing, or that sort of thing), it is unlikely that you could successfully force her to wear hijab; often, people of that age in that situation will simply wear hijab when going out the door and then take it off once they get to school, or wherever.
(An exception would be in a place where wearing hijab is the norm, and not wearing hijab outdoors would attract a lot of attention, in which case I would definitely consider it prudent to push a young woman to wear hijab, but I am assuming that this is not your situation.)
As you say, adults react poorly to compulsion, and will usually turn against anything they are forced to do.
While this may or may not be relevant, it is worth keeping in mind that women sometimes change their hairstyles (or hijab-styles) as a reflection of other life changes - such a change in family status (a broken engagement, a parent's divorce/remarriage, etc), a change in their inner outlook and sense of who they are, or life challenges. So, sometimes, the hijab in and of itself is not really the main thing that is going on, even if it is the most visible one.
It might be worth interrogating why hijab is leading to a dislike of Islam itself. Are there women around who wear hijab who are behaving poorly? Are you living in a place where hijab is stigmatized? Does she just want to express herself more through her clothes or live a different kind of lifestyle? Is it just teenage rebellion? There are all sorts of scenarios, many of which have nothing to do with actual fiqh rulings about hijab.
In any case, discussing the underlying issues - which hijab is often symbolic of - and trying to come to some sort of agreement with her about her clothing might be more fruitful.
The main underlying purpose behind hijab seems to be discouraging harassment or misconduct from men and encouraging modest interactions.
When it comes to protecting girls from sexual harassment or indecent conduct from men, I certainly don't think that a girl has to be mature enough to understand things that her parents tell her to do. For instance, parents might tell a child not to wear certain things in public, not to go certain places alone, not to talk to certain people, not to get into a car with a stranger, not to talk to strangers online, etc.
The parents say these things because the child isn't usually old enough to understand them.
Of course boys should be protected too, but usually there is an extra concern about girls.
Obviously the hijab does not wholly prevent harassment or misconduct, and it is wrong to say that it does, but since discouraging harassment and encouraging modest interactions seems to be the underlying purpose behind it, this is the angle I am responding from.
There are other things surrounding the hijab such as presenting one's identity as a Muslim. Most children who are nine years old are able to understand that and verbalize it to others (e.g. "I wear hijab because I am Muslim") if they have been raised in a religious family or environment.
Of course, I understand that hijab can be stressful in a minority situation and there may be things that the child is not yet ready to handle, such as Islamophobia or bullying. This might be a different situation. However, these are more situation-related, not related to the main idea of hijab.
Allah The Glorious knows everything which is necessary for human beings, that is why He orders us to do it as a compulsory act and not an optional act e,g. Praying the daily prayers, fasting during the month of Ramadan, paying Khums and Zakat, etc.
Wearing Hijab is compulsory on every Muslim female because it is essential to protect her dignity and save her and the society from harm. Allah says in Quran: O Prophet! Tell your wives and your daughters and women of the believers to draw their cloaks ( veils) all over their bodies, so that they will known ( as pious women) so that they will not be harmed. (Sura 33, Verse 59).
We as Muslims believe in the Absolute Wisdom of Allah (SWT) which means that every order from Him is based on full wisdom for our benefit.
Hijab is compulsory on every Muslim female, with no difference between married or unmarried. Hijab means covering the whole hair and body of the female except her face and paws. The dress should not be tied showing the size of the body nor transparent.
There is a hadith that says:
لا طاعة لمخلوق في معصية الخالق
There is no obedience to a creation through disobedience to the Creator.
We cannot obey the laws of others at the cost of disobeying Almighty God. If hijab has been mandated by Almighty God, then we as His worshippers must comply to His law. So, we must not disobey God just to follow what someone else says, even if they are our parents whom we must obey. Our obedience to our parents is obligatory, but not in performing haram acts.
Clearly, in this case, the parents have a misconstrued approach to how their daughter should appear or conduct herself in public. They might be under the impression that by doing this, she will get married, but of course this is the worst way and its a very damaging approach.
The daughter should not comply with what her parents want, and respectfully decline, by explaining how unhealthy this approach is.
It's not just a matter of religion, but also on a human value and social level as well.
In Islam, attraction should not be by the gazing of onlookers, but by personality and moral qualities and righteousness.
With prayers for your success.
The previous answer is complete; I just wanted to add that "not being mentally ready" could mean a number of different things.
My first impression when reading that was that it could mean she is not mentally ready to wear the hijab in a minority society (or a Muslim area where hijab is uncommon) - for instance, at a school where there are no other girls who wear hijab, and she might be under pressure to explain herself (but not be able to do so yet), or be teased, ostracized, or bullied, especially if she is shy or sensitive and does not have an assertive personality or a strong ability to stand up for herself.
In some places, Islamophobic harassment might also be a concern.
Not that it necessarily has anything to do with her personal sexuality.
I just wanted to add that because sometimes there is a tendency to discuss the hijab wholly in the context of sexuality or modesty, wheres in minority societies, the main challenges and pressures regarding hijab are usually social and relate to things like Islamophobia.
In any case, it is good to acknowledge, respect, and nurture the inherent maturity of young people. Even if they are still maturing in many ways, throughout much of history, young people have taken on many lifelong commitments at a young age, such as apprenticing to a profession, training in sports or the arts, or a religious conversion. Of course it is also good to acknowledge the limits of a child's maturity, since one doesn't expect someone who is 9 to be mature in every way. Still, in this day and age, in some societies, everyone who is under 18 is treated as a child which does not benefit them either; it is good to have a balance.
Inner and outer modesty, chastity and hijab is something Almighty God has mandated for all men and women.
It is necessary for us as Muslims to familiarise ourselves with the many benefits of inner and outer hijab, and the earlier we learn this the better.
Young boys need to be modest, and so do young girls, even though they might not be intellectually mature enough. As long as they are aware of their surroundings, and have entered into the age of religious maturity, they become responsible and accountable for what they do.
This is what bulugh and takleef means.
Furthermore, being modest and having hijab does not necessarily mean one is sexually active. It is a process of engaging with the natural and mental development of a male/female.
An Islamic lifestyle prepares us for the world, and whether this particular girl might be mentally ready or not, she must adapt to what it is that our religion wants from us, as the Almighty has accommodated to all that is required for us in our natural needs as humans.
A young girl who reaches the age of taklif will realise how beneficial and positive hijab is when she prioritises her spiritual and moral conduct over everything else, and she will realise how intellectually mature she becomes.
As for the age of bulugh, for a female it is completion of 9 lunar years. For a male, it is the occuring of one of the following, whichever one occurs first is the sign of his bulugh:
1. having a wet-dream.
2. growth of thick pubic hair.
3. completing of 15 lunar years.
And Allah knows best.
First of all, we as Muslims believe that Allah is The All Knowing, Most Wise, Most Merciful and we believe that everything comes from Him is based on full wisdom for our interest, that is why we never question His Wisdom in any matter. We believe that the full reason is best known by Allah (SWT), the Messenger (SAWA) and Ahlul Bayt (AS) who are the real successors of the Prophet (SAWA).
We also believe that our human abilities of thinking are limited and can never reach to everything. We know for sure that every order from Allah (SWT) is based on our benefit and we don't question the details.
Hijab is obligatory on females because Allah (SWT) who created males and females made males more attracted to females than females to males in usual situations. Hair of man can be attractive to some females in some situations but females are in general are much more attractive to males. This can be one of the reasons. Men are responsible to work hard to earn livelihood for their families. Hijab of women is for maintaining her dignity, modesty, safety and honour. Hijab also provide safe atmosphere away from sinful acts. Allah (SWT) says in Quran about Hijab on women (So that they are known so that they should not be harmed ( كي يُعرَفنَ فلا يؤذَين)) 33:59).
Muslim female must keep herself away from harmful exposure to non Mahram men. Full Hijab is must and she should not allow any misuse to her photo or video especially if she is young or looks attractive.
'It is permissible for Muslim woman to teach or guide others through Internet including YouTube etc after being sure that she is abiding to the Islamic teachings which aims to protect her from any type of exploitation.
As long as he is a male, and a non-mahram, a woman must observe outer and inner hijab in his presence.
She cannot remove her veil in front of gay men.
As for lesbian women, she does not need to wear hijab in front of them, as long as she knows there is no haram entailed, like lustful gazes. In the case that there is, it is best for her to cover up.
And Allah knows best.