Deuteronomy 21:13

and she shall put the raiment of her captivity from off her, all these acts being in the nature of purifying rites, Leviticus 14:8; Numbers 8:7, and shall remain in thine house, and bewail her father and her mother a full month, that is, her separation from them; and after that thou shalt go in unto her, in the relation peculiar to marriage, and be her husband, and she shall be thy wife. During this month the woman would have time even inwardly to detach herself from her previous relations and to adjust herself to the idea of joining the people of God, if possible, to be filled with genuine affection for the God of Israel and also for the man, whose action in declaring his readiness to marry her had saved her from the position and lot of a slave.