Hi Raoul, what makes you think so ? For me this appears to be an apt fit for a stoic. If we treat everything as an opinion, we can take it with a pinch of salt and tread ahead of the absolute which usually causes a staunch response.
For source I’d guide you towards Goodreads https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.goodreads.com/quotes/73368-everything-we-hear-is-an-opinion-not-a-fact-everything&ved=2ahUKEwix8OG059fqAhXLbsAKHc60Ck0QFjAKegQIAxAB&usg=AOvVaw1NDY9JAhSkHnjwMXDS2NPr
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