The European Council for Fatwa and Research issued the following: “There is a consensus amongst Muslims, historically and currently, that polygamy is permissible, and that it is not allowed for a Muslim to have more than four wives at any one time. Further, that if a Muslim has two or more wives he should practice equality of provision and abode amongst them. For Allah Almighty says: “…marry women of your choice two or three or four; but if ye fear that ye shall not be able to deal justly (with them) then only one or (a captive) that your right hands possess. That will be more suitable to prevent you from doing injustice.” (An-Nisa’: 3)
We know of no clear evidence from the Qur’an and Sunnah, which encourages the Muslim to either keep to one wife, or to polygamy. However, it has been narrated that Prophet Muhammad (peace and blessings be upon him) said: “Whosoever had two wives and treats one of them more favorably than the other will come on the Day of Judgment bent to one side.” (Reported by Ahmad, Abu Dawud, An-Nasa’i and Ibn Majah) This hadith warns against polygamy should the man not be able to practice equality amongst his wives.