출애굽기 11:7의 주석

לא 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.

ולכל בני ישראל לא יחרץ כלב לשונו, "not a single dog will whet his tongue against any Israelite, etc." Why was this so important? If the meaning of the line is that not a single Israelite would die as a result of a bite by a dog, why did the Torah not spell this out?

לא יחרץ כלב, the angel proceeds to afflict and kill the firstborn of the Egyptians. By contrast, the Jewish firstborn did not even have to endure the barking of a dog.