Romans 3
4God forbid: yea, let God be true, but every man a liar; as it is written, That thou mightest be justified in thy sayings, and mightest overcome when thou art judged.
5But if our unrighteousness commend the righteousness of God, what shall we say? Is God unrighteous who taketh vengeance? (I speak as a man)
6God forbid: for then how shall God judge the world?
That may be what you were thinking about.
Aslan is not a Tame Lion