Some may try to prove that Hijab is not an obligation anymore considering some verses of the Holy Qur'an in this regard but not all the verses. They forgot that Hijab is one of the limits which set by Allah (SWT) and who transgresses it, in fact, stands out against Him.
Some argue that the Qur’an commanded Muslim free women to cover their hair as it was needed to distinguish free woman from the female slave, [1] so now the necessity is over and Muslim women are at their ease to wear Hijab or not. But, I do not know why and how they ignore other verses of the Qur’an that address all the Muslim women saying that: “… tell the believing women to lower their gaze and be modest and guard their private parts and not expose their adornment except that which [necessarily] appears thereof, and to wrap [a portion of] their head covers over their chests…” [2] In Medina at the time of the Prophet (P) it was prevalent among the women to use the veil which covered the head and hair, but they were putting the end of the veil (Khemar) on their back, so their neck, ear and some parts of their shoulders and chest were appeared. Therefore, the Qur’an commanded them to put the end of their veil on their bosom to cover it as well as their head and hair. Referring to the latter verse, is it still possible to say Hijab is optional?
[1] Chapter 33, verse 59. ... يا أَيهَا النَّبِي قُلْ لِأَزْوَاجِكَ وَبَنَاتِكَ وَنِسَاءِ الْمُؤْمِنِينَ يدْنِينَ عَلَيهِنَّ مِنْ جَلَابِيبِهِنَّ ذَلِكَ أَدْنَى أَنْ يعْرَفْنَ فَلَا يؤْذَينَ
[2] Chapter 24, verse 31. ... وَقُلْ لِلْمُؤْمِنَاتِ يغْضُضْنَ مِنْ أَبْصَارِهِنَّ وَيحْفَظْنَ فُرُوجَهُنَّ وَلَا يبْدِينَ زِينَتَهُنَّ إِلَّا مَا ظَهَرَ مِنْهَا وَلْيضْرِبْنَ بِخُمُرِهِنَّ عَلَى جُيوبِهِنَّ