I had a student ask me if he could work with me for free so I gave him a few tasks to do. He did great work on them. When he graduated he asked me for a letter

I had a student ask me if he could work with me for free so I gave him a few tasks to do. He did great work on them. When he graduated he asked me for a letter of recommendation and I gladly wrote one for him. He used it to apply for a job at a big corporation and they put him to work fixing Y2k issues in their very old software. I've long since lost touch with him but have no doubt he's done well.