The Brazilian winger joined the Gunners in the 2020/21 campaign on a free transfer from Chelsea.
He struggled at the North London club scoring just once in his 37 appearances for the club last season.
Willian initially signed a three-year contract but was terminated in August on mutual consent.
He later joined Brazillian side Corinthians on a free transfer and reveals why he left the Emirates.
“I wasn’t happy. That’s why I didn’t perform. I don’t want to go into the details,” Willian stated via Rio Ferdinand’s YouTube channel Five.
“When I arrived there I was happy, from the beginning I was motivated, I wanted to do well – new club, new mates, new project.
“But after three months, I said to my agent: ‘Please, I want to go’. I don’t want to speak bad about the club, because it is a big club. Arsenal has a big history.
“In football, big players played there before as well. But it didn’t work, it didn’t work. It was, of course, the most difficult time of my career.
“It was big money that I gave up. But sometimes money is not the most important thing in life. I think you need to be happy, get pleasure every day waking up in the morning to go to train. I wasn’t having that.
“So I said to myself, with my family, I cannot stay here, I am not happy here. I have to leave, find a way out, leave the club, because if I stay I am going to stay the same. For me, it’s unfair to stay in a place that you don’t want to stay just because of the money. For me, it was that.”
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