Park signed for QPR yesterday.
"Ji's a fantastic player and a real players' player," Ferdinand told ManUtd.com. "He's been greatly appreciated by the other lads and the fans of our club over the years. He's been a great servant and never been any trouble. He's just a real selfless player who has always played for his team-mates and he was part of a very successful period for the club.
"I'm sad to see him go because he's a really good lad as well - after three or four years he really came out of his shell and was one of the lads, making a lot of jokes. As I said I'm sad to see him go as he's a really nice guy."