Did I do the right thing?

So I apologize in advance if this is long. I'll try to make it as short as possible. I was working on my garden this afternoon and mowing the yard and stuff and my neighbor (about 85ish?) came to his side of the fence and I walked over to talk to him. He just recently took in his son's pit bull and it followed him over to the gate as well. We were talking for a little bit and then he started to pet the dog and said that I could too if I wanted, so I reached down to pet him and he bit me and would not let go. Blood started pouring everywhere and I am a diabetic so my thumb was swelling and ended up being 3x its size when it was all said and done with. I ended up having to go to the ER and he offered to do my yard work and stuff around the house and pay my hospital bills as I don't have good insurance so I probably will end up paying a lot. My friend told me I was wrong (mind you, his wife just passed away a couple weeks ago and they are still paying for her funeral) so I told him not to worry about it. My friend then told me that I was wrong and he should have paid. I just couldn't do that. What should I have done?