It is given in the Holy Quran:
….marry the women you like and who are lawful for you, two or three or four (but this sanction is conditional on justice). Then if you fear that you will not be able to treat (more than one wife) justly then (marry) only one woman. Surah Nisa (4:3)
In the Shariah, it is the responsibility of the person who marries more than once to be equally just with both wives. Even in the fulfillment of conjugal rights, this equality has to be maintained. If the husband spends one night with one wife, then he should spend one night with the other also; if 2 nights with one wife, then the same number of nights with the other. If he cannot maintain justice between 2 wives, then on the Day of Judgment, one of his hands will be cut. As given in this Hadith:
Translation of Hadith: It has been narrated on the authority of Hadhrat Abu Hurairah (May Allah be well pleased with him) that the Holy Prophet (Sallallahu alaihi wa sallam) said: If a person who has 2 wives and he does not maintain justice between them, then in Qiyamah, he will come with one of his hands cut.
(Jame' Tirmidhi, Hadith No: 1171)
Thus, the husband should realize his responsibility and fulfill the right of both the wives and maintain justice between them while doing so.
In case, someone is mistreating his wife, this should be explained in the best possible manner to the husband and the elder, influential people of the family/community should also be asked to do so. As given in Fatawa A'alamgiri, Kitab Un Nikah.
In the same way demanding that husband leave the second wife is not the Islamic way. In demanding the rights of one’s sister/daughter, etc. we cannot deprive another Muslim lady of her rights without any mistake of hers.
And Allah (Subhanahu Wa Ta'ala) knows best.
Mufti Syed Ziauddin Naqshbandi Qadri,
[Naib Shaykh Ul Fiqh, Jamia Nizamia,
Founder/Director Abul Hasanaat Islamic Research Center]