5 All the offspring of Jacob were seventy persons: and Joseph had come to Egypt before them. 6 Then Joseph came to his end, and all his brothers, and all that generation. 7 And the children of Israel were fertile, increasing very greatly in numbers and in power; and the land was full of them.
Matthew Henry's Commentary on Exodus 1:5-7
Commentary on Exodus 1:1-7
(Read Exodus 1:1-7)
During more than 200 years, while Abraham, Isaac, and Jacob lived at liberty, the Hebrews increased slowly; only about seventy persons went down into Egypt. There, in about the same number of years, though under cruel bondage, they became a large nation. This wonderful increase was according to the promise long before made unto the fathers. Though the performance of God's promises is sometimes slow, it is always sure.