Deuteronomy 25:5-6

Respect for the Sanctity of Others

25:5 If brothers live together and one of them dies without having a son, the dead man’s wife must not remarry someone outside the family. Instead, her late husband’s brother must go to her, marry her, and perform the duty of a brother-in-law. 25:6 Then the first son she bears will continue the name of the dead brother, thus preventing his name from being blotted out of Israel.