Ruth 3:12-13

3:12 Now yes, it is true that I am a guardian, but there is another guardian who is a closer relative than I am. 3:13 Remain here tonight. Then in the morning, if he agrees to marry you, fine, let him do so. But if he does not want to do so, I promise, as surely as the Lord lives, to marry you. Sleep here until morning.”

Genesis 38:8

38:8 Then Judah said to Onan, “Have sexual relations with your brother’s wife and fulfill the duty of a brother-in-law to her so that you may raise up a descendant for your brother.”

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.

Matthew 22:24

22:24 “Teacher, Moses said, ‘If a man dies without having children, his brother must marry the widow and father children for his brother.’

Luke 20:28

20:28 They asked him, “Teacher, Moses wrote for us that if a man’s brother dies leaving a wife but no children, that man must marry the widow and father children for his brother.