Acts 7:25

For he supposed. Rather, “but he was supposing,” even as he slew the Egyptian. He took for granted that the Hebrews would understand his deed and its motives. He was quickly disillusioned. This insight into the mind of Moses is not drawn from the OT, but could have been given to Stephen by the Holy Spirit. The speaker may also be suggesting a comparison between Moses and Jesus, who were both rejected by the people whom they sought to help.

By his hand. Apparently it had been revealed to Moses that he was to deliver Israel, but he was under the misapprehension that the work was to be accomplished by the same sort of means the Egyptians commonly used to enforce their power.

They understood not. A terse but effective phrase, highlighting the obtuseness of the chosen people. God’s people too often do not understand, and are unready for, God’s acts of deliverance (cf. the Jewish attitude toward Christ, John 1:11).