A person wishing to perform Hajj on behalf of one of his parents, should he perform it on behalf of his mother or his father?

Q: Last year, I performed the obligatory Hajj. I hope your Eminence would advise me on the following question: This year, I wish to perform Hajj on behalf of one of my parents: Should I perform Hajj on behalf of my mother or my father? Please advise me. May Allah reward you with the best reward. Please be informed that my parents passed away, may Allah be merciful with them. If Allah wills, I am (Part No. 10; Page No. 42) intending to perform Hajj this year. Kindly accept my deep appreciation for you. As-salamu `alaykum warahmatullah wabarakatuh (May Allah's Peace, Mercy, and Blessings be upon you.)

A: You should perform Hajj on behalf of the parent who did not perform the obligatory Hajj in his of her life. If neither of them performed Hajj, you should perform Hajj for your mother first and the next time for your father.May Allah grant us success. May Peace and Blessings of Allah be upon our Prophet Muhammad, his family and his Companions.