if he will

Ruth 2:20
Then Naomi said to her daughter-in-law, "May he be blessed by the LORD, who has not withdrawn his kindness from the living or the dead." Naomi continued, "The man is a close relative. He is one of our kinsman-redeemers."

Ruth 4:5
Then Boaz said, "On the day you buy the land from Naomi and also from Ruth the Moabitess, you must also acquire the widow of the deceased in order to raise up the name of the deceased on his inheritance."

Deuteronomy 25:5-9
When brothers dwell together and one of them dies without a son, the widow must not marry outside the family. Her husband's brother is to take her as his wife and fulfill the duty of a brother-in-law for her. . . .

Matthew 22:24-27
"Teacher, " they said, "Moses declared that if a man dies without having children, his brother is to marry the widow and raise up offspring for him. . . .

the Lord liveth

Judges 8:19
"They were my brothers, " Gideon replied, "the sons of my mother! As surely as the LORD lives, if you had let them live, I would not kill you."

Jeremiah 4:2
and if you can swear, 'As surely as the LORD lives, ' in truth, in justice, and in righteousness, then the nations will be blessed by Him, and in Him they will glory."

2 Corinthians 1:23
I call God as my witness that it was in order to spare you that I did not return to Corinth.

Hebrews 6:16
Men swear by someone greater than themselves, and their oath serves as a confirmation to end all argument.