C. F. Keil and Franz Delitzsch on Deuteronomy 10:22

Deu 10:22

One marvel among these great and terrible acts of the Lord as to be seen in Israel itself, which had gone down to Egypt in the persons of its fathers as a family consisting of seventy souls, and now, notwithstanding the oppression it suffered there, had grown into an innumerable nation. So marvellously had the Lord fulfilled His promise in Gen 15:5. By referring to this promise, Moses intended no doubt to recall to the recollection of the people the fact that the bondage of Israel in a foreign land for 400 years had also been foretold (Gen 15:13.). On the seventy souls, see at Gen 46:26-27.