President Nelson said it this way: 
"Obedience brings success; exact obedience brings miracles."^[v]

Our family and mission version is "Obedience brings blessings, but exact obedience brings miracles."
...
I am sure that I do not completely understand what exact obedience means, but here is what I have come to understand. It is not perfect obedience; that is impossible. Hence, repentance must be a key part of exact obedience. 
-Brother M. Joseph Brough, "Heeding the Voice of the Lord," BYU-Idaho Devotional