(How can ye take it (back)) how can you take the dowry back as a lawful possession. (after one of you hath gone in unto the other) when you have come together under one cover as a result of this dowry and marriage, (and they have taken) He says: Allah has taken from you upon marrying women (a strong pledge from you?) a firm pledge that you either keep them in goodness or release them in kindness. Then Allah forbade them from marrying the wives of their fathers, since this is what they did in the pre-Islamic era.
