Acts 7:6
And God spake on this wise, That his seed should sojourn in a strange land; and that they should bring them into bondage, and entreat them evil four hundred years. And God spake on this wise, That his seed should sojourn in a strange land; and that they should bring them into bondage, and entreat them evil four hundred years.
Acts 7:6 was spoken as part of the defense before the council in answer to the charge of blasphemy, to vindicate the speaker's cause. It was delivered in a clear, thrilling voice that held the assembly spellbound. It was spoken amid tumult and resistance, when coming death could be read in the listeners' faces.
It was spoken at the dictation of the Holy Spirit as a last testimony to the judges. Its occasion, time, and place give it its full significance. It belongs to a rehearsal of the history of God's chosen people and His dealings with them. That rehearsal began with Abraham and traced from generation to generation through the national records of Israel to Solomon, selecting the most impressive points. It showed thorough knowledge of the Jewish economy.
That historical review preached Christ from the Old Testament beginning with Moses and the prophets. It showed that Christ had been foretold in prophecy. It gave the spiritual interpretation now made manifest through Christ. It gave inspired proof in regard to His mission, suffering, death, resurrection, and ascension. As part of Stephen's testimony from the Old Testament it showed that God spoke through the patriarchs and that their testimony points to Christ.
As prophetic evidence about Jesus it proves the identity of the crucified Jesus with the Messiah as the Son of God through the testimony of Moses and the prophets. Paul also used that same evidence for the same purpose. It was the voice of Christ speaking through the prophets and patriarchs from the days of Adam onward. Christ is the key unlocking the Old Testament.