It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "Whoever has two wives and inclines more towards one of them, he will come on the Day of Resurrection with half of his body leaning (tilted), as if it is bent due to paralysis."
In this hadith, there is a severe warning for one who is unjust among his wives, and in it, a very fine example is given of the woman being the counterpart of man (shaqa’iq al-rijal). On the Day of Resurrection, one of his sides will be drooping. If Allah grants someone the ability to have multiple wives, then justice and fairness among them is extremely necessary. It is commonly observed that when a person marries a second wife, he turns away from the first wife; this is outright oppression. Further on, there will be more ahadith regarding the rights of women.