Often it is the case that cultural tendencies take a precedent over Islamic jurisprudential and social norms. An example of this is the cultural practice of not marrying a Sayyida woman to anyone but another Sayyid man. This practice is usually witnessed more frequently in the Indo-Pakistani community.
Although the sentiments for such a culture may have some reasonings that are positive, such as continuing the Sayyid lineage, we find that the Prophet (saw) and the Ahlulbayt (as) did not restrict the marriage of the women of Bani Hashim to only their relatives.
1. Zainab, the cousin of the Prophet, who was from Bani Hashim and the granddaughter of Abdul Muttalib, married Zaid, who was a slave adopted by the Prophet. This is an early example of a non-Sayyid marrying a Sayyida under the watch of the Prophet Muhammad (saw) although it did later end in divorce.
2. Another example is the marriage of Dhuba’ah, cousin of the Prophet and granddaughter of Abdul Muttalib, with the famous companion Miqdad ibn Amr who was from Yemen. Miqdad is known as one of the most loyal companions of the Prophet who remained steadfast with Imam Ali (as) until his martyrdom.
3. Also, we have Umama, the daughter of the Prophet’s uncle Hamza; who married Salama bin Abi Salama who was not from Bani Hashim.
4. Um Hassan, the daughter of Imam Ali (as) was married to Ju’da bin Hubayr Al-Makhzuni who was not from Bani Hashim.
5. Ramla, another daughter of Imam Ali (as) was married to Sult Al-Nawfali who was not from Bani Hashim.
6. Fatima Al-Sughra, also a daughter of Imam Ali (as) was married to Saeed Al-Asadi who was not from Bani Hashim.
One of the counter arguments presented on this topic is that by ‘Sayyid’ we mean the ‘children of Sayyida Fatima (as)’ and not simply Bani Hashim. However, we find that Sayyida Zainab (as) being the direct daughter of Sayyida Fatima (as) married her cousin Abdullah ibn Jafar Al-Tayyar, showing that a marriage outside of this framework is permissible.
Among the contemporary Shia scholars, there is a unanimous opinion that a girl from Bani Hashim, known as a Sayyida, can marry a non-Sayyid.