וַיַּכְבֵּ֤ד פַּרְעֹה֙ אֶת־לִבּ֔וֹ גַּ֖ם בַּפַּ֣עַם הַזֹּ֑את וְלֹ֥א שִׁלַּ֖ח אֶת־הָעָֽם׃ (פ)
바로가 가로되 내가 너희를 보내리니 너희가 너희 하나님 여호와께 광야에서 희생을 드릴 것이나 너무 멀리는 가지 말라 그런즉 너희는 나를 위하여 기도하라
Rashi
Again this time. [Once more,] though he said, “I will send you out,” he did not keep his promise.
Ibn Ezra
And Pharaoh hardened. He hardened his heart like he did with the frogs, it is written there "and his heart hardened"
Rashbam
גם בפעם הזאת, just as G’d had stiffened Pharaoh’s heart after the relief experienced when the frogs had died, so that he had reneged on his promise.