The author of this quote is unknown.
This is particularly talking about challenges you may encounter in every life ordeal. Many obstacles will rise, especially when you decide to take an action against every moment to succeed. The devil will roar like a lion to scare you that you don’t have what it takes to attain a particular feat. Whatever stands against your success, you must be ready to stand against it. Most of the times, you need to dedicate your total commitment to a course and make up your mind that nothing would discourage you from achieving the feat. It is now left to you not to be the obstacle to your own success.