The Scottish midfielder failed to impress during his last spell in the Premier League, at Blackburn.
“I have not got a point to prove. I enjoyed it at Blackburn. I started off well but then I got a bad injury. I fractured my kneecap and I was out for seven or eight months,” he said.
“I came back from it and I played a lot of games for Blackburn. I did well. I was captain there and, even though Mark Hughes came in (to replace Graeme Souness) everything was fine.
“But it was a case of ‘when your old club comes calling’ so I kind of left under a bit of a cloud.”
Ferguson added: “I could have stayed, got a contract extension, joined other clubs who were interested, but I made my decision.
“People ask me ‘do have I any regrets?’ but things happen in life for a reason.
“I went back up the road to Rangers and I won more Championships, Scottish Cups and League Cups and got to a Uefa Cup final so I don’t think it was a bad decision!”
