TSK
Treasury of Scripture Knowledge references in NET.
Respect for the Sanctity of Others 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.
Naomi said to her daughter-in-law,“May he be rewarded by the LORD because he has shown loyalty to the living on behalf of the dead!” Then Naomi said to her,“This man is a close relative of ours; he is our guardian.”
The guardian said,“Then I am unable to redeem it, for I would ruin my own inheritance in that case. You may exercise my redemption option, for I am unable to redeem it.”
“Teacher, Moses said,‘If a man dies without having children, his brother must marry the widow and father children for his brother.’
For people swear by something greater than themselves, and the oath serves as a confirmation to end all dispute.