TSK · Leviticus 18:16

If brethren dwell together, and one of them die, and have no son, the wife of the dead shall not be married without unto a stranger: her husband's brother shall go in unto her, and take her to him to wife, and perform the duty of a husband's brother unto her.

saying, Teacher, Moses said, If a man die, having no children, his brother shall marry his wife, and raise up seed unto his brother.

Teacher, Moses wrote unto us, If a man's brother die, and leave a wife behind him, and leave no child, that his brother should take his wife, and raise up seed unto his brother.