5 "If brothers dwell together, and one of them dies and has no son, the widow of the dead man shall not be married to a stranger outside the family; her husband's brother shall go in to her, take her as his wife, and perform the duty of a husband's brother to her. 6 And it shall be that the firstborn son which she bears will succeed to the name of his dead brother, that his name may not be blotted out of Israel. 7 But if the man does not want to take his brother's wife, then let his brother's wife go up to the gate to the elders, and say, 'My husband's brother refuses to raise up a name to his brother in Israel; he will not perform the duty of my husband's brother.' 8 Then the elders of his city shall call him and speak to him. But if he stands firm and says, 'I do not want to take her,' 9 then his brother's wife shall come to him in the presence of the elders, remove his sandal from his foot, spit in his face, and answer and say, 'So shall it be done to the man who will not build up his brother's house.' 10 And his name shall be called in Israel, 'The house of him who had his sandal removed.'
Matthew Henry's Commentary on Deuteronomy 25:5-10
Commentary on Deuteronomy 25:5-12
(Read Deuteronomy 25:5-12)
The custom here regulated seems to have been in the Jewish law in order to keep inheritances distinct; now it is unlawful.