Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear sister, we really appreciate your question. We hope our efforts, exerted purely for Allah’s sake, come up to your expectations.
Sister, hijab is an aspect of chastity and modesty of a Muslim woman. It is a duty that Allah Almighty prescribes for the favor of the Muslim woman, and she has to comply with the command of Allah, thus showing her sincere faith in Allah and fear of His punishment. Allah Almighty says “And it becomes not a believing man or a believing woman, when Allah and His Messenger have decided an affair (for them), that they should (after that) claim any say in their affair.” (Al-Ahzab 33:36)
Regarding your question, we cite the following fatwa issued by the eminent scholar, Dr. Nasr Farid Wasil, former Mufti of Egypt:
When a pilgrim performs all pillars of Hajj or `Umrah, then he/she has fulfilled his/her obligation and is thus exempted from further obligation.
So, if a woman, who intends to take off hijab after Hajj or `Umrah, performed all the rituals required in the right manner and in the due time, then her Hajj or `Umrah are valid and she has fulfilled her obligation. However, whoever performs a prescribed act of worship sincerely for the sake of Allah, without intention to show off or take pride, has to abide by the teachings and manners of Islam, both during Hajj and `Umrah and after them.
In that way, a person would attain Allah’s pleasure, his reward would increase, and his Hajj or `Umrah would be accepted by Almighty Allah. The Prophet (peace and blessings be upon him) said: “The performance of `Umrah is an expiation for the sins committed between it and the previous ones. And the reward for Hajj mabrur (Pilgrimage accepted by Allah) is nothing but Paradise.” (Al-Bukhari)
Accordingly, a woman who intends to take off hijab after returning from Hajj or `Umrah must know that by so doing she has prior intention to commit a sin, and such intention is abhorrent enough to undermine the reward of Hajj or `Umrah because people are accountable for their deeds according to their intentions. So she has to refrain from such an intention and abide by the Islamic teachings, before or after Hajj, so that Allah will be pleased with her on the Day of Judgment.
Finally, we would like to quote the Prophet (peace and blessings be upon him) who said:“This House of Allah (the Ka`bah) is the pillar of Islam; so whosoever heads for it with the intention of performing Hajj or `Umrah is under Allah’s Protection. If he should die (during this journey), he will be admitted to Paradise, and if he should return home safely, he will return with reward and gain.” (Al-Haythami, Majma` Az-Zawa’id) So, dear sister, do not lose Allah’s reward or disregard His pleasure so that you will not be a loser in this life and in the life to come.
Allah Almighty knows best.