The Prophet’s Family Marrying Outside the Family

It should be clear that though we do love and respect the family of our Prophet (peace and blessings be upon him), Shari`ah does not regard them as a special or superior caste in Islam.
Dr. Muzammil H. Siddiqi, former President of the Islamic Society of North America, states: “First of all, let me correct some misconceptions. Syeds or Bani Hashim who belong to the family of the Prophet (peace and blessings be upon him) are not a special or superior caste in Islam. They are not like Brahmins in Hinduism. We love and respect our Prophet (peace and blessings be upon him) and his family. So we also respect his family, and we even extend this respect to all the people who belong to his extended family. But they have no extra privileges in Islam. They are not better Muslims simply because they are Syeds. It is not right for them to call other Muslims “regular” and consider themselves as “more” Muslims. The Syed women are not like “mothers” to other non-Syed Muslims. Only the wives of the Prophet (peace and blessings be upon him) are Mothers of the Believers. No other women from the family of the Prophet (peace and blessings be upon him) were given this title.
Also, there is no prohibition in Islam for a Syed man to marry a non-Syed woman or a Syed woman to marry a non-Syed man. Islam spread in the Indian subcontinent because it was egalitarian. It was against the caste system, but unfortunately Muslims soon adopted the Hindu caste system and made their own “dhat” (caste) system. All Muslims are equal. The best among them are those who are most conscious of Allah. Allah says, “Surely the noblest of you in the sight of Allah are those who are the most pious among you.” (Al-Hujurat: 13)
Thus, any Muslim can marry any other Muslim male or female. The Prophet (peace and blessings be upon him) himself arranged the marriage of his cousin Zaynab with his slave Zayd.
Scholars have spoken about compatibility and equality in marriage. It is good to consider the compatibility of morals, manners, religiousness, age, education, physical looks, country of origin, race, ethnicity, family background, et cetera. These things make marriage more successful and permanent. The more the bride and groom are of equal status, the more suitable they are for each other. But these things are only as recommendations for marriage. They are common sense rules; they are not conditions for the marriage in Islam.
The only marriages that are prohibited are those that are mentioned in the Qur’an in Surat an-Nisa’: 23, and Allah says in the following verse, “… except for these women, all others are lawful, provided you seek them in marriage…” (An-Nisa’: 24).”