God told him that his descendants would be foreigners in a strange land, and that they would be enslaved and mistreated four hundred years.
6. Thy seed shall be a stranger. Stephen putteth the Jews in mind in how miserable and reproachful an estate their fathers were in Egypt; and showeth that this their servitude, wherewith they were oppressed, came not by chance; because it was foretold long before by the oracle of God.
The high priest speaks with a show of fairness, yet his tone is haughty and his prejudgment plain: if Stephen has spoken such words, he shall be condemned as a blasphemer. But Stephen's answer proves him a man mighty in Scripture, filled with the Holy Ghost not to reveal new secrets, but to bring the Old Testament writings to remembrance and convict his gainsayers.
AI summary
Commenting on Acts 7:1-16
And God spake on this wise,.... The Vulgate Latin and Syriac versions read, "and God spake to him", and so does one of Beza's copies; and the Ethiopic version reads it both ways, God "said thus to Abraham", as in Gen 15:13.