'Brother in law' in the Bible

"When two brothers are living together and one of them dies without leaving a son, his widow must not be married outside the family to a foreigner. Instead, the brother-in-law must go to her, take her as his wife, and by doing so perform the duty of a brother-in-law.

But if the man does not want to marry his brother's widow, then she must go to the elders at the city gate and declare, "My husband's brother refuses to perform the duty of a brother-in-law in order to preserve the name of his brother in Israel. He is not willing to perform the duty of a brother-in-law.'

then she is to approach her brother-in-law in the presence of the elders, remove his sandal, spit in his face, and say in response, "May this be done to the man who does not preserve the lineage of his brother.'