So the quote from Tesla's autobiography My Inventions (1919) is:
"For nearly a year my regular hours were from 10.30 A.M. until 5 o'clock the next morning without a day's exception. Edison said to me: "I have had many hard-working assistants but you take the cake." During this period I designed twenty-four different types of standard machines with short cores and of uniform pattern which replaced the old ones. The Manager had promised me fifty thousand dollars on the completion of this task but it turned out to be a practical joke. This gave me a painful shock and I resigned my position."
It's not made clear who the Manager is, and it's widely believed to be Samuel Insull, who managed a great deal of the daily operations towards the end of Tesla's time with Edison (1885). Edison had withdrawn from his company a bit after the death of his wife (1884). Samuel Isnull appeared to dislike Tesla quite strongly. And AFAIK Tesla does not mention the infamous "Tesla you don't understand American humour" at all. I'd be happy to be proven wrong though.
This is Edison on Tesla in 1896:
"Tesla is an experimenter of the highest type and may produce in time all that he says he can."
This is Tesla on Edison, again from his autobiography My Inventions:
"The meeting with Edison was a memorable event in my life. I was amazed at this wonderful man who, without early advantages and scientific training, had accomplished so much. I had studied a dozen languages, delved in literature and art, and had spent my best years in libraries reading all sorts of stuff that fell into my hands, from Newton's "Principia" to the novels of Paul de Kock, and felt that most of my life had been squandered. But it did not take long before I recognized that it was the best thing I could have done."
When Tesla and Edison were discussing x-rays, Edison wrote this in his letter to Tesla in 1896:
"My dear Tesla, Many thanks for your letter. I hope you are progressing and will give us something that will beat Roentgen."
