Rashi on Exodus 8:18/רש"י על שמות ח׳:י״ח

1והפליתי means I WILL SEPARATE. Similar is, (Exodus 9:4) “And the Lord will make a separation (והפלה)”; so, also, (Deuteronomy 30:11) “It is not נפלאת from thee״ — that is, “it is not separated and set at a far distance from thee”.

2למען תדע כי אני ה׳ בקרב הארץ IN ORDER THAT THOU MAYEST KNOW THAT I AM THE ETERNAL IN THE MIDST OF THE EARTH — although My Shechina is in the heavens My command is fulfilled amongst mankind (as we might say, “My writ runs on earth also”).