Deuteronomy 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, ¹  and perform the duty of a brother-in-law. ² 

Ge 38:8,9; Ru 1:12,13; Ru 3:9; Ru 4:5; Mt 22:24; Mr 12:19; Lu 20:28

¹ tn Heb “take her as wife”; NRSV “taking her in marriage.”

² sn This is the so-called “levirate” custom (from the Latin term levir, “brother-in-law”), an ancient provision whereby a man who died without male descendants to carry on his name could have a son by proxy, that is, through a surviving brother who would marry his widow and whose first son would then be attributed to the brother who had died. This is the only reference to this practice in an OT legal text but it is illustrated in the story of Judah and his sons (Gen 38) and possibly in the account of Ruth and Boaz (Ruth 2:8; 3:12; 4:6).