Deuteronomy 25:5-10

⁵ When brothers reside together, and one of them dies and has no son, the wife of the deceased shall not be married outside the family to a stranger. Her husband's brother shall go in to her, taking her in marriage, and performing the duty of a husband's brother to her, ⁶ and the firstborn whom she bears shall succeed to the name of the deceased brother, so that his name may not be blotted out of Israel. ⁷ But if the man has no desire to marry his brother's widow, then his brother's widow shall go up to the elders at the gate and say, "My husband's brother refuses to perpetuate his brother's name in Israel; he will not perform the duty of a husband's brother to me." ⁸ Then the elders of his town shall summon him and speak to him. If he persists, saying, "I have no desire to marry her," ⁹ then his brother's wife shall go up to him in the presence of the elders, pull his sandal off his foot, spit in his face, and declare, "This is what is done to the man who does not build up his brother's house." ¹⁰ Throughout Israel his family shall be known as "the house of him whose sandal was pulled off."