if he will
Ruth 2:20
And Naomi said unto her daughter in law, Blessed be he of the LORD, who hath not left off his kindness to the living and to the dead. And Naomi said unto her, The man is near of kin unto us, one of our next kinsmen.
Ruth 4:5
Then said Boaz, What day thou buyest the field of the hand of Naomi, thou must buy it also of Ruth the Moabitess, the wife of the dead, to raise up the name of the dead upon his inheritance.
Deuteronomy 25:5-9
5
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.
6
And it shall be, that the firstborn which she beareth shall succeed in the name of his brother which is dead, that his name be not put out of Israel.
7
And if the man like not to take his brother's wife, then let his brother's wife go up to the gate unto the elders, and say, My husband's brother refuseth to raise up unto his brother a name in Israel, he will not perform the duty of my husband's brother.
8
Then the elders of his city shall call him, and speak unto him: and if he stand to it, and say, I like not to take her;
9
Then shall his brother's wife come unto him in the presence of the elders, and loose his shoe from off his foot, and spit in his face, and shall answer and say, So shall it be done unto that man that will not build up his brother's house.
Matthew 22:24-27
24
Saying, Master, Moses said, If a man die, having no children, his brother shall marry his wife, and raise up seed unto his brother.
25
Now there were with us seven brethren: and the first, when he had married a wife, deceased, and, having no issue, left his wife unto his brother:
26
Likewise the second also, and the third, unto the seventh.
27
And last of all the woman died also.
the Lord liveth
Judges 8:19
And he said, They were my brethren, even the sons of my mother: as the LORD liveth, if ye had saved them alive, I would not slay you.
Jeremiah 4:2
And thou shalt swear, The LORD liveth, in truth, in judgment, and in righteousness; and the nations shall bless themselves in him, and in him shall they glory.
2 Corinthians 1:23
Moreover I call God for a record upon my soul, that to spare you I came not as yet unto Corinth.
Hebrews 6:16
For men verily swear by the greater: and an oath for confirmation is to them an end of all strife.