Acts 7:6 - Matthew Poole's English Annotations on the Holy Bible

Should sojourn in a strange land, as men which dwell in houses that are not their own; which seem to contradict the promise mentioned in the foregoing verse; but it is only to make Abraham the more believe against hope in hope, as it is said, Romans 4:18: though there were never so many difficulties more, for what God hath promised faith would overcome them all. This very space of four hundred years is also mentioned, Genesis 15:13; which is thus computed: from the birth of Isaac (the promised seed) to the birth of Jacob, sixty years; from Jacob's birth to his going into Egypt, one hundred and thirty years; from thence to their deliverance out of Egypt, two hundred and ten years; this period is accounted, Exodus 12:40,41, to be four hundred and thirty years; which also St. Paul reckons by, Galatians 3:17; but then thirty years is added unto the account, being the space of time between the first promise made unto Abraham of this seed, and the birth of Isaac, in whom the promise was to be fulfilled; St. Stephen here reckoning only from the birth of Isaac.