The conditions of hijaab:

Shaykh al-Albaani (may Allaah have mercy on him) said:
The conditions of hijaab:
Firstly:
(It should cover all the body apart from whatever has been exempted).
Allaah says (interpretation of the meaning):
“O Prophet! Tell your wives and your daughters and the women of the believers to draw their cloaks (veils) all over their bodies (i.e. screen themselves completely except the eyes or one eye to see the way). That will be better, that they should be known (as free respectable women) so as not to be annoyed. And Allaah is Ever Oft-Forgiving, Most Merciful.”
This aayah clearly states that it is obligatory to cover all of a woman’s beauty and adornments and not to display any part of that before non-mahram men (“strangers”) except for whatever appears unintentionally, in which case there will be no sin on them if they hasten to cover it up.
Al-Haafiz ibn Katheer said in his Tafseer:

This means that they should not display any part of their adornment to non-mahrams, apart from that which it is impossible to conceal. Ibn Mas’ood said: such as the cloak and robe, i.e., what the women of the Arabs used to wear, an outer garment which covered whatever the woman was wearing, except for whatever appeared from beneath the outer garment. There is no sin on a woman with regard to this because it is impossible to conceal it.
Secondly
(it should not be an adornment in and of itself).
Allaah says (interpretation of the meaning):
“… and not to show off their adornment…” [al-Noor 24:31]. The general meaning of this phrase includes the outer garment, because if it is decorated it will attract men’s attention to her. This is supported by the aayah in Soorat al-Ahzaab (interpretation of the meaning):
“And stay in your houses, and do not display yourselves like that of the times of ignorance” [al-Ahzaab 33:33]. It is also supported by the hadeeth in which the Prophet (peace and blessings of Allaah be upon him) said: “There are three, do not ask me about them: a man who leaves the jamaa’ah, disobeys his leader and dies disobedient; a female or male slave who runs away then dies; and a woman whose husband is absent and left her with everything she needs, and after he left she made a wanton display of herself. Do not ask about them.”
(Narrated by al-Haakim, 1/119; Ahmad, 6/19; from the hadeeth of Faddaalah bint ‘Ubayd. Its isnaad is saheeh and it is in al-Adab al-Mufrad).
Thirdly:
(It should be thick and not transparent or “see-thru”)
- because it cannot cover properly otherwise. Transparent or see-thru clothing makes a woman more tempting and beautiful. Concerning this the Prophet (peace and blessings of Allaah be upon him) said: “During the last days of my ummah there will be women who are clothed but naked, with something on their heads like the humps of camels. Curse them, for they are cursed.” Another hadeeth adds: “They will not enter Paradise or even smell its fragrance, although its fragrance can be detected from such and such a distance.”
(Narrated by Muslim from the report of Abu Hurayrah).
Ibn ‘Abd al-Barr said: what the Prophet (peace and blessings of Allaah be upon him) meant was women who wear clothes made of light fabric which describes and does not cover. They are clothed in name but naked in reality.
Transmitted by al-Suyooti in Tanweer al-Hawaalik, 3/103.
Fourthly:
(It should be loose, not tight so that it describes any part of the body).
The purpose of clothing is to prevent fitnah (temptation), and this can only be achieved if clothes are wide and loose. Tight clothes, even if they conceal the colour of the skin, still describe the size and shape of the body or part of it, and create a vivid image in the minds of men. The corruption or invitation to corruption that is inherent in that is quite obvious. So the clothes must be wide. Usaamah ibn Zayd said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) gave me a thick Egyptian garment that was one of the gifts given to him by Duhyat al-Kalbi, and I gave it to my wife to wear. He said, ‘Why do I not see you wearing that Egyptian garment?’ I said, ‘I gave it to my wife to wear.’ He said, ‘Tell her to wear a gown underneath it, for I am afraid that it may describe the size of her bones.’” (Narrated by al-Diyaa’ al-Maqdisi in al-Ahaadeeth al-Mukhtaarah, 1/442, and by Ahmad and al-Bayhaqi, with a hasan isnaad).
Fifthly:
(It should not be perfumed with bakhoor or fragrance)
There are many ahaadeeth which forbid women to wear perfume when they go out of their houses. We will quote here some of those which have saheeh isnaads:

1. Abu Moosa al-Ash’ari said: the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Any woman who puts on perfume then passes by people so that they can smell her fragrance, is an adulteress.”
2. Zaynab al-Thaqafiyyah reported that the Prophet (peace and blessings of Allaah be upon him) said: “If any one of you (women) goes out to the mosque, let her not touch any perfume.”
3. Abu Hurayrah said: the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Any woman who has scented herself with bakhoor (incense), let her not attend ‘Ishaa’ prayers with us.”

4. Moosa ibn Yassaar said that a woman passed by Abu Hurayrah and her scent was overpowering. He said, “O female slave of al-Jabbaar, are you going to the mosque?” She said, “Yes,” He said, “And have you put on perfume because of that?” She said, “Yes.” He said, “Go back and wash yourself, for I heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say: ‘If a woman comes out to the mosque and her fragrance is overpowering, Allaah will not accept any prayer from her until she goes home and washes herself.’”

These ahaadeeth are general in implication. Just as the prohibition covers perfume applied to the body, it also covers perfume applied to the clothes, especially in the third hadeeth, where bakhoor (incense) is mentioned, because incense is used specifically to perfume the clothes.
The reason for this prohibition is quite clear, which is that women’s fragrance may cause undue provocation of desires. The scholars also included other things under this heading of things to be avoided by women who want to go to the mosque, such as beautiful clothes, jewellery that can be seen, excessive adornments and mingling with men. See Fath al-Baari, 2/279.
Ibn Daqeeq al-‘Eed said:
This indicates that it is forbidden for a woman who wants to go to the mosque to wear perfume, because this causes provocation of men’s desires. This was reported by al-Manaawi in Fayd al-Qadeer, in the commentary on the first hadeeth of Abu Hurayrah quoted above.
Sixthly:
(It should not resemble the clothing of men)
It was reported in the saheeh ahaadeeth that a woman who imitates men in dress or in other ways is cursed. There follow some of the ahaadeeth that we know:

1. Abu Hurayrah said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) cursed the man who wears women’s clothes, and the woman who wears men’s clothes.”
2. ‘Abd-Allaah ibn ‘Amr said: I heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say: ‘They are not part of us, the women who imitate men and the men who imitate women.’”
3. Ibn ‘Abbaas said: “The Prophet (peace and blessings of Allaah be upon him) cursed effeminate men and masculine women. He said, ‘Throw them out of your houses.’” He said: “The Prophet (peace and blessings of Allaah be upon him) expelled So and so, and ‘Umar expelled So and so.” According to another version: “The Messenger of Allaah (peace and blessings of Allaah be upon him) cursed men who imitate women and women who imitate men.”
4. ‘Abd-Allaah ibn ‘Amr said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘There are three who will not enter Paradise and Allaah will not even look at them on the Day of Resurrection: one who disobeys his parents, a woman who imitates men, and the duyooth (cuckold, weak man who feels no jealousy over his womenfolk).”

5. Ibn Abi Maleekah – whose name was ‘Abd-Allaah ibn ‘Ubayd-Allaah – said: “It was said to ‘Aa’ishah (may Allaah be pleased with her), ‘What if a woman wears (men’s) sandals?’ She said: ‘The Messenger of Allaah (peace and blessings of Allaah be upon him) cursed women who act like men.’”

These ahaadeeth clearly indicate that it is forbidden for women to imitate men and vice versa, This usually includes dress and other matters, apart from the first hadeeth quoted above, which refers to dress only.
Abu Dawood said, in Masaa’il al-Imaam Ahmad (p. 261): “I heard Ahmad being asked about a man who dresses his slave woman in a tunic. He said, ‘Do not clothe her in men’s garments, do not make her look like a man.” Abu Dawood said: “I said to Ahmad, Can he give her bachelor sandals to wear? He said, No, unless she wears them to do wudoo’. I said, What about for beauty? He said, No. I said, Can he cut her hair short? He said, No.”
Seventhly:
(It should not resemble the dress of kaafir women).
It is stated in sharee’ah that Muslims, men and women alike, should not resemble or imitate the kuffaar with regard to worship, festivals or clothing that is specific to them. This is an important Islamic principle which nowadays, unfortunately, is neglected by many Muslims, even those who care about religion and calling others to Islam. This is due either to ignorance of their religion, or because they are following their own whims and desires, or because of deviation, combined with modern customs and imitation of kaafir Europe. This was one of the causes of the Muslims’ decline and weakness, which enabled the foreigners to overwhelm and colonize them. “…Verily, Allaah will not change the condition of a people as long as they do not change their state themselves …” [al-Ra’d 13:11 – interpretation of the meaning]. If only they knew.
It should be known that there is a great deal of saheeh evidence for these important rules in the Qur’aan and Sunnah, and that the evidence in the Qur’aan is elaborated upon in the Sunnah, as is always the case.
Eighthly:
(It should not be a garment of fame and vanity).
Ibn ‘Umar (may Allaah be pleased with him) said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘Whoever wears a garment of fame and vanity in this world, Allaah will clothe him in a garment of humiliation on the Day of Resurrection, then He will cause Fire to flame up around him.’”
(Hijaab al-Mar’ah al-Muslimah, p. 54-67).
And Allaah knows best.
Hijaab al-Mar’ah al-Muslimah, p. 54-67