Mourinho advised Sahin the Barclays Premier League would be good for his development.
"We spoke and he told me that English football, especially the Premier League, is the best to enjoy as a footballer," the former Borussia Dortmund man said.
"Every weekend you can enjoy football. He also told me about how he and Brendan Rodgers worked together at Chelsea and that he's a good coach and person. That's important for me. It's not only football, it was very important for me to have someone who I can speak with."