Acts 7:27 (KJV)

And Moses was learned in all the wisdom of the Egyptians, and was mighty in words and in deeds.

And when he was full forty years old, it came into his heart to visit his brethren the children of Israel.

And seeing one of them suffer wrong, he defended him, and avenged him that was oppressed, and smote the Egyptian:

For he supposed his brethren would have understood how that God by his hand would deliver them: but they understood not.

And the next day he shewed himself unto them as they strove, and would have set them at one again, saying, Sirs, ye are brethren; why do ye wrong one to another?

Wilt thou kill me, as thou diddest the Egyptian yesterday?

Then fled Moses at this saying, and was a stranger in the land of Madian, where he begat two sons.

And when forty years were expired, there appeared to him in the wilderness of mount Sina an angel of the Lord in a flame of fire in a bush.

When Moses saw it, he wondered at the sight: and as he drew near to behold it, the voice of the LORD came unto him,

Saying, I am the God of thy fathers, the God of Abraham, and the God of Isaac, and the God of Jacob. Then Moses trembled, and durst not behold.