Rashi on Exodus 11:7/רש"י על שמות י״א:ז׳

1לא יחרץ כלב לשנו NO DOG SHALL חרץ HIS TONGUE — I say that it has the meaning of sharpening: “no dog shall whet his tongue”. So, too: (Joshua 10:21) “לא חרץ his tongue against any of the children of Israel”, i. e. “none whetted”; (II Samuel 5:24) “then תחרץ” — then thou shalt utter a sharp sound; (Isaiah 41:15) “a threshing-sledge חרוץ” i. e. sharp; (Proverbs 21:5) “the plans of a חרוץ” — of “an acute and sharp man”; (Proverbs 10:4) “the hand of the חרוצים maketh rich”, i. e. the hand of the acute — of sharp merchants.

2אשר יפלה meant THAT HE MAKETH A DIFFERENCE.