[Nisa 4:20] And if you wish to change one wife for another and you have given her heaps of treasure, do not take back anything from it; will you take it back by slander and open sin?

[Nisa 4:21] And how will you take it back whereas you have become unveiled before each other, and they have taken a strong pledge from you?

[Nisa 4:22] And do not marry the women who were wedded to your fathers (and grand fathers), except what has already passed; that is indeed an act of shame and great wrong; and an evil way.

Section 4

[Nisa 4:23] Forbidden for you are your mothers, and your daughters, and your sisters, and your father�s sisters, and your mother�s sisters, and your brothers� daughters and your sisters� daughters, and your foster-mothers (who breast-fed you), and their daughters (your foster-sisters), and your wives� mothers (mothers-in-law), and your wives� daughters who are under your protection - born of the women with whom you have cohabited; and if you have not cohabited with them, then it is no sin for you to marry their daughters; and (forbidden are) the wives of your own sons (and foster-sons and grandsons) and the keeping of two sisters together in marriage, except what has already passed; indeed Allah is Oft Forgiving, Most Merciful.