We know about Tom Robinson throughout the hearing by hearsay and through some of the evidence that is spoken in court. However, on chapter 19 there is a specific incident in which Link Deas, Tom Robinson's employer had to stand up in court and yelled out:
“I just want the whole lot of you to know one thing right now. That boy’s worked for me eight years an’ I ain’t had a speck o’trouble outa him. Not a speck.”
Additionally, we now that Tom had offered the Ewells to do favors for them in order to help them with the notoriously huge burden that they carry with so many children and so little money. In fact, he used to offer his help before and after work without expecting any money or pay in return.
Therefore, we can safely conclude from the above that Tom Robinson was, indeed, a hard working man.