Answer
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.
In this fatwa:
The belief you have mentioned is just a superstition; it has no base of reason or revelation.
In his response to your question, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
It is just superstitious if someone thinks that if two siblings get married at the same time, it will make their marriage miserable. Since it has no basis in reason or revelation, it is high time for us to put to rest such superstitions.
The only way to eliminate them is through education and raising the consciousness of people. You should be practical and take the initiative and get your peers and leaders in the community to work to remove such misconceptions.
The Prophet (peace and blessing be upon him) said, “Whoever sets the precedent or example for a noble deed, he or she will be receiving the same reward as everyone who follows the lead.” (Ibn Majah)
Marital happiness is not dependent on such practices. Marriage can be a blessing or curse depending on other relevant factors, including our attitude, behavior, relationship with Allah Almighty and surrender to His will, as well as fairness and kindness towards each other, and, last but not least our willingness to compromise, forgive, and establish proper communication.
Allah Almighty knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.
Source: Excerpted, with slight editorial modification, from askthescholar.com