TSK · Ruth 3:2

¶ If brethren dwell together, and one of them die, and have no child, the wife of the dead shall not marry 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 an husband's brother unto her.

Then said Boaz unto Ruth, Hearest thou not, my daughter? Go not to glean in another field, neither go from hence, but abide here fast by my maidens:

For both he that sanctifieth and they who are sanctified [are] all of one: for which cause he is not ashamed to call them brethren,