Acts 7:23

And when he was full forty years old Better, But when he was well-nigh forty years old. The verb in the original intimates that the forty years were just being completed. For the fixing of this time we have no authority in the Old Testament. We learn thence that Moses was eighty years old when he was sent to speak before Pharaoh for the deliverance of the Israelites (Exodus 7:7), and that he was a hundred and twenty years old when he died (Deuteronomy 34:7). In Midrash Tanchumaon Exodus 2:6, we are told "Moses was in the palace of Pharaoh twenty years, but some say fortyyears, and forty years in Midian, and forty years in the wilderness." Stephen's words agree with this tradition.

it came into his heart to visit his brethren the children of Israel The verb in the original, which is here rendered visit, is the same as in Luke 7:16, "God hath visited his people," and means to look upon (generally with kindness, James 1:27), and this was the old sense of the English visit. Cf. Shaks. Rich. II. 1. 3. 275:

"All places that the eye of heaven visits."