Revelation 15:3

And they sing the song of Moses, the servant of God, and the song of the Lamb, saying, Great and wonderful are thy works, Lord God Almighty; just and true are thy ways, O King of the nations?

Romans 12:2

And be not conformed to this world, but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect will of God.

Treasury of Scripture Knowledge

Summary

As for God, his way is perfect: the word of the LORD is tried: he is a buckler to all those that trust in him.

Bible References

His way

Romans 12:2
And be not conformed to this world, but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect will of God.
Revelation 15:3
And they sing the song of Moses, the servant of God, and the song of the Lamb, saying, Great and wonderful are thy works, Lord God Almighty; just and true are thy ways, O King of the nations?