Deuteronomy 29:2-4

2This is what Moses said to all the Israelites when they met together: You have seen everything that the Lord did in Egypt. You saw how he punished Egypt's king, his officers and his whole country.

3You saw the miracles which the Lord did to show his great power.

4But until now the Lord has not let you understand why he did that. You saw and you heard those things, but you did not understand.