One fine sunny day a young fisherman was out catching fish with his faithful companion, which he named Ralph. Despite the fisherman not being all that good at catching fish, Ralph did an excellent job at it. He ran into the river and snatched those fish up and put them in the bucket, leaving them with dozens of them to take home and feast on together.
So one day, after catching their daily load, they were encountered by what appears to be a man with great riches. He had a large grey mustache with a big black suit and a great big belly with a monocle on his eye.
“Excuse me, sir,” said the rich man, “I have been watching you and your dog catch fish for quite some time now, and it would be in my greatest interest to buy your pet there for $500”
“Ugh…” said the fisherman, “I don’t know about that. Ralph here has been helping me catch so many fish for so many years, and I couldn’t imagine life without him. Besides, I love him so much…”
“Now look here,” replied the rich man, “I will give you $100,000 dollars for that precious dog of yours, so I could use it for the circus”
“Hmm…” The fisherman thought. He thought high, he thought low, until he finally came with a decision.
“I’m sorry, sir, but I’ve decided I do not want to sell my dog for $100,000, $1,000,000, or even $1. I love my dog and he has done so much for me, and he catches so much fish for me I can’t live without him”
The rich man huffed and went away, and the fisherman and his dog Ralph hugged each other happily.

Extremely obvious moral: Family, friends, and pets shouldn’t be sold for all the money in the world.

Third Aesop. Sorry it features the humans instead of the dog.