Deuteronomy 25:5-7

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 go in to her and take her to himself as wife and perform the duty of a husband’s brother to her.

6It shall be that the firstborn whom she bears shall 2assume the name of his dead brother, so that 3his name will not be blotted out from Israel.

74But if the man does not desire to take his brother’s wife, then his brother’s wife 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.’