Exodus 17:9–10
9 So Moses said to gJoshua, “Choose for us men, and go out and fight with Amalek. Tomorrow I will stand on the top of the hill with hthe staff of God in my hand.” 10 So gJoshua did as Moses told him, and fought with Amalek, while Moses, Aaron, and iHur went up to the top of the hill.
Exodus 24:13
13 So Moses rose with his assistant kJoshua, and Moses went up linto the mountain of God.
Exodus 33:11
11 Thus dthe Lord used to speak to Moses face to face, as a man speaks to his friend. When Moses turned again into the camp, his eassistant Joshua the son of Nun, a young man, would not depart from the tent.