First of all God is God he needs no proving, in another video bro soriano Vividly explain to us how God created the entire universe the whole world even we humans system is complicated enough to let us know that some supreme being is responsible for this make up....
About today's question Bro Eli just took us back into over 3500 years a go about the miracles and wonders God did in the land of Egypt....
Remember When God asked MOSES to go to Egypt to deliver the Israelite, one of the assurance that God Gave Moses was that he will prove himself before pharoah
We have read of the many numerous Signs and wonders God performed through MOSES that was God proving himself to pharoah that he is the Only true and wise God, even when pharoah brought all his magician to test MOSES rod, that turned Into snakes MOSES own swallowed all their gods...
Even till Today God is still proving himself strong in our lives through the various testimonies we encountered along the way.