וּלְכֹ֣ל ׀ בְּנֵ֣י יִשְׂרָאֵ֗ל לֹ֤א יֶֽחֱרַץ־כֶּ֙לֶב֙ לְשֹׁנ֔וֹ לְמֵאִ֖ישׁ וְעַד־בְּהֵמָ֑ה לְמַ֙עַן֙ תֵּֽדְע֔וּן אֲשֶׁר֙ יַפְלֶ֣ה יְהוָ֔ה בֵּ֥ין מִצְרַ֖יִם וּבֵ֥ין יִשְׂרָאֵֽל׃
Но против любого из сынов Израилевых не будет пса языком его против человека или зверя; чтобы вы знали, как Господь устанавливает разницу между египтянами и Израилем.
Rashi
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.
Chizkuni
לא יחרץ כלב לשונו, “not a single dog will whet its tongue;” it was customary for the dogs to bellow at midnight as midnight was the time when the watches changed as we know from the Talmud in B’rachot folio 3. When the Israelites made ready to leave, each one with his walking stick in his hand, these watchdogs did not raise their voices in protest and gave no alarm.
Da'at Zekenim
ולכל בני ישראל לא יחרץ כלב לשונו, “but not a single dog raised his voice against a single Israelite.” This was the miracle; normally dogs alert their owners to the presence of the angel of death in their midst. In this instance, not one of the watch dogs wagged as much as a tail to warn their owners of danger.