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."
Matthew Henry's Commentary on Deuteronomy 25:7
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.