'Brother in law' in the Bible

"When brothers dwell together and one of them dies and has no son, the wife of the deceased shall not become the wife of a {man of another family}; her brother-in-law {shall have sex with her}, and he shall take her {to himself} as wife, and he shall perform his duty as brother-in-law [with respect to] her.

But if the man [does] not want to take his sister-in-law, then his sister-in-law shall go up to the gate, to the elders, and she shall say, 'My brother-in-law refused {to perpetuate his brother's name} in Israel, [for] he is not willing {to marry me}.'