7 And if the man like not to take his brother's wife, then his brother's wife shall go up to the gate unto the elders, and say, My husband's brother refuseth to raise up unto his brother a name in Israel; he will not perform the duty of a husband's brother unto 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.