Doug Lesmerises did an interview with the author of Saban: The Making of a Coach, Monte Burke.

One excerpt from the interview, "...I did hear there's not a lot of love lost between the two."

Also, it goes into some detail about when Saban was an assistant under Earle Bruce at OSU, and that the two did not see eye to eye very well. The reasoning behind this was that Saban viewed Bruce as living in the past and not wanting to adapt, at the time, to the changing of the game.

I find this point hilarious because Saban is doing exactly what he thought Bruce was doing back then. He does not want to deal with the new spread offenses, and complains about them every chance he gets. As the article puts it, he is a "purist." 

Here is the entire story:

http://www.cleveland.com/osu/index.ssf/2015/08/nick_saban_book_and_urban_meye.html