Wa`alykum As-Salamu Warahmatullahi Wabarakatuh.
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 questioner! Thanks a lot for your question and the interest you show in having a clearer view of the true teachings of Islam. May Allah help you get the right understanding and stand firm on the Straight Path! Amen!
In Islam, marriage is a solemn contract for which the Shari`ah lays down rules and arrangements to guarantee its stability. Though Islam permits man to have more than a wife, it stipulates that certain conditions are to be met in this regard, for Islam’s main focus is on building a stable marital life.
Answering your question, Sheikh M. S. Al-Munajjid, a prominent Saudi Muslim lecturer and author, states:
“If a man is able to take a second wife, physically and financially, and he can treat both wives in a just manner, and he wants to, then he is allowed to do so according to Islam. Allah says, “Then marry (other) women of your choice, two or three, or four.” (An-Nisa’: 3)
It is well known that women are by nature jealous and reluctant to share their husband with other women. Women are not to be condemned for this jealousy, for it existed in the best of righteous women, the wives of the Companions, and even in the Mothers of the Believers. But women should not let jealousy make them object to that which Allah has permitted, and they should not try to prevent it; a wife should allow her husband to marry another woman for this is a kind of cooperating in righteousness and piety.
The first wife’s consent is not a prerequisite for a man to take another wife. The Standing Committee for Issuing Fatwas was asked about this and replied as follows:
It is not obligatory for the husband, if he wants to take a second wife, to have the consent of his first wife, but it is good manners and kindness to deal with her in such a manner that will minimize the hurt feelings such thing might produce. So it’s incumbent on the husband to be kind to his wife, discuss the matter with her in a gentle and pleasant manner, and this should be coupled with spending whatever money may be necessary in order to gain her acceptance of the situation.”
Excerpted, with slight modifications, form: www.islam-qa.com
So in the light of the above, it’s clear that the matter is not just having a right to do so, it’s how you use that right. As we have said in many fatwas how Islam caters for the rights of women, men should not tamper with rights that Islam made inalienable to women, part of which is to respect their humanity. They are not property that can be done with at any time without any consideration; women are life partners.