The Rules of Marriagewww.bellaonline.com/articles/art47144.asp
Chapter 4, verse 22-23
Do not marry the women who were previously married to your fathers - existing marriages are exempted and shall not be broken - for it is a gross offense, and an abominable act.
Prohibited for you are your mothers, your daughters, your sisters, the sisters of your fathers, the sisters of your mothers, the daughters of your brother, the daughters of your sister, your nursing mothers, the girls who nursed from the same woman as you, the mothers of your wives, the daughters of your wives with whom you have consummated the marriage - if the marriage has not been consummated, you may marry the daughter. Also prohibited for you are the women who were married to your genetic sons. Also, you shall not be married to two sisters at the same time - but do not break up existing marriages. GOD is Forgiver, Most Merciful.