TSK · Leviticus 18:16

Respect for the Sanctity of Others 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.

“Teacher, Moses said,‘If a man dies without having children, his brother must marry the widow and father children for his brother.’

“Teacher, Moses wrote for us:‘If a man’s brother dies and leaves a wife but no children, that man must marry the widow and father children for his brother.’