1. An act of Obedience.
The Hijaab is an act of obedience to Allaah and to his Prophet (sallallahu 'alayhi wa sallam). Allaah (subhaanahu wa ta'aala) says in the Qur'an, {It is not for a believer, man or woman, when Allaah and His messenger have decreed a matter that they should have an option in their decision. And whoever disobeys Allaah and His Messenger, has indeed strayed in a plain error.} (S33:36).
Allaah, the Almighty also said, {And tell the believing women to lower their gaze (from looking at forbidden things) and protect their private parts (from illegal sexual acts, etc) and not to show off their adornment except what must (ordinarily) appear thereof, that they should draw their veils over their Juyoobihinna.} (S24:31).
The respected scholars differ whether the Jilbaab (outer-garment) must include the hands and face or not. Some say that the hands and face must be covered. Other respected scholars say it is preferable for women to cover their whole bodies.
2. The Hijaab is 'Iffah (Modesty).
Allaah (subhaanahu wa ta’aala) made the adherence to the Hijaab a manifestation for chastity and modesty. Allaah (subhaanahu wa ta'aala) says, {O Prophet! Tell your wives and your daughters and the women of the believers to draw their cloaks (veils) over their bodies (when outdoors). That is most convenient that they should be known and not molested.} (S33:59). In the above verse there is evidence that the recognition of the apparent beauty of the woman is harmful to her. Allaah, the Almighty, has made it permissible for elderly women to lay aside their outer garments and expose their faces and hands’, still reminding them, however, that it is still better for them to keep their modesty.
3. The Hijaab is Tahaarah (Purity)
Allaah (subhaanahu wa ta'aala) has shown us the Hikmah (wisdom) behind the legislation of the Hijaab. {And when you ask them (the Prophet's wives) for anything you want, ask them from behind a screen, - that is purer for your hearts and their hearts.}
The hijaab brings about greater purity for the hearts of both believing men and women because it screens against the evil desires of the heart. Without the Hijaab, the heart may or may not desire. But with the hijaab the very temptation of evil glances and advances are prevented. The Hijaab cuts off ill thoughts and the greed within the sick hearts, {Be not soft in speech, lest he in whose heart is a disease (of hypocrisy or evil desire for adultery, etc) should be moved with desire, but speak in an honourable manner.} (S33:32)
4. The Hijaab is a Shield
The Prophet (sallallahu `alayhi wa sallam) said, "Allaah, Most High, in Heaven, is Ha'yeii (Bashful), Sit'teer (Shielder). He loves Hayaa' (Bashfulness) and Sitr (Shielding; Covering)."
The Prophet (sallallahu `alayhi wa sallam) also said, "Any woman who takes off her clothes in other than her husband's house (to show off for unlawful purposes), has broken Allaah's shield upon her.”
5. The Hijaab is Taqwah (Righteousness)
Allaah, the Almighty says in the Qur'an, {O children of Adam! We have bestowed raiment upon you to cover yourselves (screen your private parts, etc) and as an adornment. But the raiment of righteousness, that is better.} (S7:26). The widespread forms of dresses in the world today are mostly for showing off and are hardly taken as a cover and shield for the woman's body. For the believing women, however the purpose is to safeguard their bodies and cover their private parts as a manifestation of the order of Allaah... It is an act of Taqwah (righteousness).
6. The Hijaab is Eemaan (Belief or Faith)
Allaah (subhaanahu wa ta'aala) addresses the command regarding the Hijaab to the Muslim Women by referring to them as Al-Mu’minaat (the believing women) and this occurs many times in the Qur’aan. 'Aa'ishah (radhiallahu 'anhaa), the wife of the Prophet (sallallahu 'alayhi wasallam), addressed some women from the tribe of Banoo Tameem who came to visit her and had light clothes on them and hence were improperly dressed,
"If indeed you are believing women, then truly this is not the dress of the believing women, and if you are not believing women, then enjoy it."
7. The Hijaab is Haya' (Bashfulness)
There are two authentic hadith which state, "Each religion has a morality and the morality of Islam is shyness." And, "Bashfulness is from belief, and belief is in Al-Jannah (paradise)".
The Hijaab fits the natural bashfulness which is a part of the nature of women.
8. The Hijab is Gheerah (Commendable Jealousy)
The Hijaab fits the natural feeling of Gheerah, which is intrinsic in the righteous man who does not like people to look at his wife or daughters. Gheerah is a driving emotion that drives the straight man to safeguard women who are related to him from the eyes and contact of strangers. In fact, the Muslim man should have Gheerah for all Muslim women.
The mixing of sexes and absence of Hijaab destroys the Gheerah in men. Islam considers Gheerah as an integral part of faith. The dignity of the wife or daughter or any other Muslim woman must be highly respected and defended.