Plague five begins with the same message that opened the demands at the Nile. Targum Pseudo-Jonathan on Exodus 9:1: Thus saith the Lord, the God of the Jehudaee, Emancipate My people, that they may worship before Me.
The meturgeman, writing in late antiquity, makes the anachronism deliberate. The Hebrew says God of the Hebrews; the Aramaic says God of the Jehudaee — the God of the Jews. For the Aramaic-speaking congregation hearing the Targum read out on Shabbat, there is no gap between the slaves of Egypt and themselves. The same God is speaking, the same demand is being made, the same oppressor is being addressed in every generation.
Four plagues have fallen, and Pharaoh is about to hear the identical command for the fifth time. The repetition is the point. God does not grow tired of saying let My people go until they are let go. Prophets do not move on to new topics. Every time Moses is sent, he says the same line. The only variable is how long Pharaoh will make him say it before listening.
And there is a subtle dignity here. God keeps calling Israel My people even while they are in chains. The slaves have not yet been redeemed, but they are already owned — by the right Owner. The status changes because of relationship, not because of geography.
The takeaway: you can be enslaved and be God's people at the same time. Redemption is not the moment you become His. Redemption is the moment the world acknowledges what you already were.