Sean Smith was sad to learn Brandon Browner will spend the next 8 years behind bars ... 'cause Smith says the guy helped him when the 2 were in jail -- and the place was awful.
TMZ Sports broke the story ... Browner pled no contest to attempted murder Tuesday -- and was sentenced to 8 years in state prison.
When Smith -- an ex-NFL DB who did time in an LA jail with Browner over the summer -- saw the news ... he was heartbroken for the former Seahawk, saying time behind bars ain't a joke.
"Jus seen some news about my dawg B Browner smh," Smith wrote on social media.
"It’s crazy how I was JUST in there with him. He for sure helped me get thru the last few months in that hell hole. Jail is for animals."
Smith just got out in August roughly 5 months into his 12-month sentence for assaulting his sister's boyfriend during a July 4, 2017 incident in Pasadena, CA.
He says his time behind bars sucked ... and he hopes Browner's close friends stay by him to help through the sentence like Brandon did for him over the summer.
"I don’t wish it on nobody, damn I can only imagine smh. If y’all his 'real friends' reach out!!!"