Speaking on Rio Ferdinand's official YouTube channel, Willian said: "I was not happy, that's why I didn't perform. I don't want to go into the details, but I wasn't happy. When I arrived there I was happy, from the beginning I was motivated.
"I wanted to do well, new club, new mates, new projects. After three months, I told my agent 'please, I want to go'. I don't want to speak bad about the club because it is a big club, has a big history in football, big players played there.
"But it didn't work, it was of course the most difficult time of my career. It was big money that I gave up — money is not the most important thing in life, you need to be happy, to be getting pleasure and wake up and want to go to training.
"I wasn't having that, so I said to myself, with my family and my wife 'I cannot stay here, I am not happy at Arsenal, I have to leave.' For me, it is unfair to stay in a place you don't want to stay just because of the money."
Willian signed a three-year contract at Arsenal in the summer of 2020 after failing to agree a new deal with another Premier League side from London, Chelsea.
The Brazilian left the Emirates after spending a year with the Gunners and scoring just once in 37 games, terminating his contract by mutual consent.
