Montesquieu
 

XVI.7 On equality of treatment in the case of multiple wives

From the law on plu­ra­lity of wives fol­lows the law on equa­lity of treat­ment. Mohammed, who allows for four, would have eve­ry­thing equal among them : food, clo­thing, conju­gal duty. This law is also esta­bli­shed in the Maldives, where a man may marry three wives.1

The law of Moses even requi­res that when someone has mar­ried his son to a slave, and later he mar­ries a free woman, he should dimi­nish none of her clo­thing, food, and duties.2 More could be given to the new wife, but the first wife must not have less.

Voyage de François Pyrard, chap. xii.

Exodus 21:10-11.