Ambrose of Milan

The history of the Jews, who went down into Egypt and came out from Egypt, seems to accord with this. The years they spent there were 430, but not all of them lived a hundred years and more, as did Moses and Joshua, so that the time of the fourth generation would be appropriate in this context. So let us search rather for a mystical sense. In fact, the number four adapts well to all numbers, and it is in a certain sense the root and base of the decimal. It also represents the midpoint of the number seven. …

On Abraham ↗

Jerome

But in the fourth generation they will return here. There is no doubt that these will be the ones who are descended from Abraham. It is asked how it is written in Exodus: In the fifth generation the children of Israel went forth from the land of Egypt (Exodus 15:18). On this chapter, we have published a small volume.

Hebrew Questions on Genesis ↗

Bede

But in the fourth generation, they shall return here. Kohath entered Egypt with his father Levi, whose son was Amram, whose son was Aaron, whose son was Eleazar, who was the fourth from Kohath. And he went out from Egypt with his father Aaron, and when he died in the wilderness, he himself entered the Promised Land.

Commentary on Genesis (Hexaemeron) ↗