Nu 23:21 "He has not observed iniquity in Jacob, Nor has He seen wickedness in Israel..."
Israel's history before this has been wayward, unbelieving and rebellious many a time. Israel, no doubt, has been marked by iniquity and wickedness. But, here, God is said to have not observed and seen iniquity and wickedness in Israel. How is that?
The Bible, elsewhere says: "Blessed is the man to whom the LORD shall not impute sin or iniquity." (see Psalm 32:2)
God, in Numbers 23:21, looked ahead, into the future, when Israel, as a nation, will repent and turn to the Savior, the Lord Jesus Christ, in faith. By then, the Lord Jesus Christ, as the Lamb of God, will take away all their sins, and they will be covered with the robe of His righteousness.
Isa 61:10 says: "I will greatly rejoice in the LORD, My soul shall be joyful in my God; For He has clothed me with the garments of salvation, He has covered me with the robe of righteousness, As a bridegroom decks himself with ornaments, And as a bride adorns herself with her jewels."
My friend, Israel's future blessing can be your present enjoyment if you turn to the Lord Jesus Christ in faith, trusting in Him and what He did on the cross for your justification. Yes, you may be marked with iniquity and wickedness but, in Him, God will never see and observed in you any sin at all. In Him, you will be covered with His perfect righteousness.