Deuteronomy 25:5-9

5“When brothers live together, and one of them dies and has no son, the wife of the deceased shall not be married outside the family to a strange man. 1Her husband’s brother shall have relations with her and take her to himself as his wife, and perform the duty of a husband’s brother to her.

6It shall then be that the firstborn to whom she gives birth shall 2assume the name of his father’s deceased brother, so that 3his name will not be wiped out from Israel.

74But if the man does not desire to take his brother’s widow, then his brother’s widow shall go up to the gate to the elders, and say, ‘My husband’s brother refuses to establish a name for his brother in Israel; he is not willing to perform the duty of a husband’s brother to me.’

8Then the elders of his city shall summon him and speak to him. And if he persists and says, ‘I do not desire to take her,’

95then his brother’s widow shall come up to him in the sight of the elders, and pull his sandal off his foot and 6spit in his face; and she shall 7declare, ‘This is what is done to the man who does not build up his brother’s house!’