A new employee joined our company 2 months ago. He was a newbie (well, I am not a pro either, but I definitely know more than he does) so he often asked me for help. And today when I arrived at work I noticed that he was absent. When I asked my boss where he was, he said that the newbie had been fired because he was not productive. My boss said I was doing a lot of his work and I had to stay longer at the office to finish my own projects on time. It seems that he was fired because of me and that's not really a good feeling.
Does this mean that we should not help co-workers when they ask for it? What would be best way to tell them that you are not going to help them?