He said (cited by Daily Record): “Celtic signed me and although I didn’t speak English, in my first year there I had a great season. Then Manchester United came in for me. They offered £9 million, but Celtic wanted £15 million so it never happened.”
It is evident that he was a decorated Celtic player and therefore it is understandable why Celtic demanded a premium for his services.
Prior to that, he played for Al-Fayha as well. However, his family struggled to adapt in Saudi Arabia and he decided to return to Celtic for a second spell.