Jehovah, through the angel, provided credentials that Moses could present to the older men of Israel. These were in the form of three miracles as signs. Here, for the first time in the Scriptures, we read of a human empowered to perform miracles.​—Ex 4:1-9.

The first miracle that Aaron performed before Pharaoh at Moses’ direction proved Jehovah’s supremacy over the gods of Egypt, even though Pharaoh became more obstinate. (Ex 7:8-13) Later, when the third plague occurred, even the priests were forced to admit, “It is the finger of God!” And they were so severely stricken by the plague of boils that they were altogether unable even to appear before Pharaoh to oppose Moses during that plague.​—Ex 8:16-19; 9:10-12.

Plagues do softening and hardening work. Moses and Aaron became the announcers of each of the Ten Plagues. The plagues came as announced, proving Moses’ commission as Jehovah’s representative. Jehovah’s name was declared and much talked about in Egypt, accomplishing both a softening and a hardening toward that name​—softening the Israelites and some of the Egyptians; hardening Pharaoh and his advisers and supporters. (Ex 9:16; 11:10; 12:29-39) Instead of believing that they had offended their gods, the Egyptians knew that it was Jehovah who was judging their gods. By the time nine plagues had been executed, Moses too had become “very great in the land of Egypt, in the eyes of Pharaoh’s servants and in the eyes of the people.”​—Ex 11:3.

There was a marked change in the men of Israel also. They had at first accepted Moses’ credentials, but after experiencing harder working conditions at the order of Pharaoh, they complained against him to the point that Moses in discouragement appealed to Jehovah. (Ex 4:29-31; 5:19-23) The Most High at that time strengthened him by revealing that He was now going to fulfill that for which Abraham, Isaac, and Jacob had looked, namely, the full revealing of the meaning of his name Jehovah in delivering Israel and establishing it as a great nation in the land of promise. (Ex 6:1-8) Even then the men of Israel did not listen to Moses. But now, after the ninth plague, they were solidly behind him, cooperating so that, after the tenth plague, he could organize them and lead them out in an orderly way, “in battle formation.”​—Ex 13:18.