Exodus 2:11-13

11 One day, after Moses had grown up, he went out to his people and saw their forced labor. He saw an Egyptian beating a Hebrew, one of his kinsfolk.
12 He looked this way and that, and seeing no one he killed the Egyptian and hid him in the sand.
13 When he went out the next day, he saw two Hebrews fighting; and he said to the one who was in the wrong, "Why do you strike your fellow Hebrew?"