Commentaire de citation sur Les Psaumes 78:44

ויחזק לב פרעה, “Pharaoh’s heart remained stubborn, strong.” The reason why Pharaoh did not ask Moses to pray for the removal of this plague was that this would have been an admission that it was a heavenly phenomenon. [Besides thus far none of the plagues had caused deaths, only inconvenience. He felt that if this is all that Hashem can do, he could live with it. Ed.] There was a good reason to feel that a plague which was common among the poor people all the time, had spread for some reason beyond its normal boundaries. Pharaoh did not realise that the absence of a warning meant that this was not of Moses’ doing; in fact the reason why he had not been warned was that he had ignored the warnings issued before the first two plagues, so that this was the punishment for having ignored those two plagues to influence his attitude toward the Israelite slaves. Moreover, every group of three plagues, as pointed out by Rabbi Yehudah who characterised (summarised) them as acronyms, i.e. דצ׳ך, עד׳ש, באח׳ב, was also introduced by Moses as having a specific objective.(Compare Exodus 8,6: למען תדע כי אין כה׳ אלוקינו “so that you will realise that there is no G-d like our G-d.” Exodus 8,18: למען תדע כי אני ה׳ בקרב הארץ, “so that you will realise that I am the Lord right here on earth also.” Exodus 9,29: למען תדע כי לה׳ הארץ, “so that you will realise that the earth belongs to the Lord.”) Some commentators explain that the reason Rabbi Yehudah summarised the plagues as he did, was to remind us that this was the correct order, as compared to Psalms 78,44-51 where they are listed in a different sequence. Also in Psalms 105, 28-36 they are listed in a different order.