God is able to do all things ... everything ... but there are some things that He will not do because He's set up rules for Himself and He cannot , He will not, violate His rules for Himself. This is His integrity.
He lives by the rules He's set up for Himself. This is what makes Him a "just" God ... because if His rules are set up just for us and He says, "I am not going to abide by them ... I made those rules for you" ... then He's not a "just" God.
The integrity of His Word ... if we learn what His integrity is for Him, then it's better and easier for us to see and use it for ourselves, for our integrity. We make His rules ours, meaning that here's the realm where we can operate. But when we go past this, we're no longer in the freedom sense of it because we have crossed the border.
Reverend Robert W. & Mary C. Butler