Psalm 93:5 Thy testimonies are very sure: Holiness becometh thine house,O LORD, for ever.
When God says something it is true. It will happen and you never have to doubt it. His testimonies are not just sure they are very sure.
Holiness is what decorates Him and His house. We can not that there is no darkness in Him. There is no lie there. There is no failure in Him. He is all that He says that He is.
Notice the words for ever. His testimonies are sure, very sure, for ever. Holiness is something that is a permanent characteristic. Truthfulness is a permanent characteristic.
I can be sure that as I read the Bible that it is true and God will do all that He says He will do. He will not change. He will not decide that one day He has a different opinion about my salvation. He is honest and holy!