Deuteronomy 21:13
13 And let her take off the dress in which she was made prisoner and go on living in your house and weeping for her father and mother for a full month: and after that you may go in to her and be her husband and she will be your wife.
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Matthew Henry's Commentary on Deuteronomy 21:13
Commentary on Deuteronomy 21:10-14
(Read Deuteronomy 21:10-14)
By this law a soldier was allowed to marry his captive, if he pleased. This might take place upon some occasions; but the law does not show any approval of it. It also intimates how binding the laws of justice and honour are in marriage; which is a sacred engagement.