Exodus 4:14

4:14 Then the Lord became angry with Moses, and he said, “What about your brother Aaron the Levite? I know that he can speak very well. Moreover, he is coming to meet you, and when he sees you he will be glad in his heart.

Exodus 5:2

5:2 But Pharaoh said, “Who is the Lord that I should obey him by releasing Israel? I do not know the Lord, and I will not release Israel!”