The Real Madrid legend will face United in the Champions League semifinals.
Raul told the Daily Mail: "Ferguson has always praised me and that means a lot because he is one of the greatest coaches in the history of football. It is very difficult to be in a big club for so many years - even with English football culture being more accustomed to longevity of coaches - and it strikes me as incredible that he goes on producing very competitive teams year after year.
"Now they have a mix of great veterans like Giggs, Scholes, Rio Ferdinand and Edwin van der Sar but also with younger players like Nani and Wayne Rooney, who is one of the world's top strikers. They are not playing the kind of football that Barcelona play but they are always competitive and always fighting in finals and semi-finals for top honours. Every year it's the same story."
So how close was he to moving to Manchester United at the end of last season?
"There was a possibility and the only person who knows if it was a real possibility or not is Ferguson. It never went as far as me talking with him, but there was contact."