All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Allaah ordained His Muslim slaves to ask Him for guidance to His straight path which is His true religion. The straight path includes the words and actions the person performs as well as the true belief in Allaah, these could be called acts of worship, or habits like eating and dressing.
But there is a connection between what is felt inwardly and what is expressed in outward acts. What is in the heart, like feelings and emotions, is a reflection of the deeds, words and other aspects of life. Similarly, the outside and apparent matters that occur affect the feelings and emotions of the heart. That's why 'Umar Ibn Al-Khattaab said when he saw a man moving in the prayer, 'Had this man's heart been reverent his limbs would have showed reverence as well'.
That's why Allaah ordered the Muslims to be different from the non-Muslims, and forbade imitating them.
A person, who wears the clothing of the people of knowledge, finds that inwardly he is somehow affiliating with them. So, wearing Hijab, being an apparent conduct, pushes the heart to abide by many meanings and conditions, the most important of which is the saying of Allaah (interpretation of meaning): {"….Allaah wishes only to remove Ar-Rijs (evil deeds and sins, etc.) from you, O members of the family (of the Prophet and to purify you with a thorough purification.}[33:33]. This verse is mentioned after Allaah forbade women to dress immodestly. Wearing Hijab makes the woman feel dignified, honoured, and chaste, and it enlightens her heart.
By wearing Hijab, a Muslim believing woman feels the taste of Eemaan.
Moreover, wearing Hijab motivates purification of the believers' hearts, males and females, motivates them to become more pious, and causes them to consider forbidden matters as being grave sins.
Allaah says (interpretation of meaning): {….that is purer for your hearts and for their hearts…..}[33:53].
In addition to this, Hijab is a means of preserving bashfulness which is crucial for the Muslim's life. It incites women to do good and drives them away from perversion. It is also a means of preserving protective jealously.
Allaah, The Truthful, says (interpretation of meaning): {And they ask you (O Muhammad concerning the Rooh (the Spirit); Say: "The Rooh it is one of the things, the knowledge of which is only with my Lord. And of knowledge, you (mankind) have been given only a little."}[17:85].
All the commandments of Allaah, including Hijab, are for the purification and uprightness.
Allaah knows best.