After five seasons together, the Oakland Raiders and offensive tackle Donald Penn have mutually agreed to part ways.

That's according to ESPN's Adam Schefter, who reported the split on Saturday following a separate report of Penn's release.

"It was a difficult decision," the lineman wrote in a farewell letter to Raiders fans posted on Twitter, "but one that I feel is best for my career, because I still feel I have years left in me as a starter in the NFL."

A three-time Pro Bowler, the 35-year-old Penn restructured his contract with the Raiders before the 2018 season but will reportedly save the team $5.475 million in 2019 by heading elsewhere. Originally undrafted in 2006, he signed with Oakland in 2014 after eight years with the Tampa Bay Buccaneers, starting at left tackle before the arrival of first-round draft pick Kolton Miller in 2018.

The Raiders have seemingly been bent on replacing Penn since drafting Miller, shifting the former to right tackle in 2018. His final season with Oakland was cut short after just four games because of a groin injury that landed him on Injured Reserve.