This event is part of Chapter 15 of Frankenstein; or the Modern Prometheus, a novel by English author Mary Shelley.
In this part of the story, the monster notices that the De Lacey family is unhappy, however, he does not know why at first. Upon learning that their troubles are due to their poverty, the moster feels guilty. He has been stealing food from them, and in that way, contributed to their struggles. In order to deal with his guilty conscience, he starts helping the De Laceys secretly which chores such as cutting wood for them to burn at their fireplace.