Abraham Lincoln by Noah Brooks

[Anita]

Gene, after reading this review I did some searching about Lincoln giving Bowling Greene's eulogy. I came across this. "When, in 1841, Green died at age fifty-­four of a stroke, “Aunt Nancy,” as Lincoln came to call her, asked him to give the eulogy at Green’s funeral. He was unable, however, to complete his tribute to his friend, breaking down in tears and leaving the stand. At the conclusion of the service he escorted Aunt Nancy to a waiting carriage to see her home. On behalf of the Widow Green, Lincoln successfully sued Mentor Graham on a note Graham owed them.[49]"
https://quod.lib.umich.edu/j/jala/262986...w=fulltext
This is the first time I've read that Lincoln sued Mentor Graham on behalf of Widow Green. Can you shed some light on this? Thanks