Deuteronomy 25:7-9

7“But if the man refuses to marry his brother’s widow, she must go to the town gate and say to the elders assembled there, ‘My husband’s brother refuses to preserve his brother’s name in Israel—he refuses to fulfill the duties of a brother-in-law by marrying me.’

8The elders of the town will then summon him and talk with him. If he still refuses and says, ‘I don’t want to marry her,’

9the widow must walk over to him in the presence of the elders, pull his sandal from his foot, and spit in his face. Then she must declare, ‘This is what happens to a man who refuses to provide his brother with children.’