Deuteronomy 25:5-6

Laws Concerning Levirate Marriage

5 a  If brothers dwell together, and one of them dies and has no son, the wife of the dead man shall not be married outside the family to a stranger. Her b  husband’s brother shall go in to her and take her as his wife and perform the duty of a husband’s brother to her. 6And the first son whom she bears shall succeed to the name of his dead brother, that c  his name may not be blotted out of Israel.
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