Albert Barnes Commentary Exodus 2:11

"And it came to pass in those days, when Moses was grown up, that he went out unto his brethren, and looked on their burdens: and he saw an Egyptian smiting a Hebrew, one of his brethren." — Exodus 2:11 (ASV)

Went out to his brethren - At the end of 40 years. The Egyptian princess had not concealed from him the fact of his belonging to the oppressed race, nor is it likely that she had prevented him from contact with his foster-mother and her family, whether or not she became aware of the true relationship.

An Egyptian - This man was probably one of the overseers of the workmen, natives under the chief superintendent (Exodus 1:11). They were armed with long heavy scourges, made of a tough pliant wood imported from Syria.