Numbers 13:30

ויהס כלב AND CALEB STILLED [THE PEOPLE] — he caused all of them to be silent. אל משה means he silenced them that they should hear what he was going to say about Moses. He cried aloud saying: “Is this the only thing the son of Amram has done to us?!" — One who heard him thus speaking believed that he was about to speak to his disparagement, and because they had something in their mind against Moses through the spies’ statements, all of them kept silent to hear his disparagement. He, however, said: “Did he not divide the Red Sea for us, and bring down the Manna for us, and collect the quails for us?!” (Sotah 35a). עלה נעלה WE CAN INDEED GO UP — even to heaven, if he were to say “Make ladders and go up there”, we should listen to him because we would be successful in all his words (in all he bids us do) (Sotah 35a). ויהס is an expression denoting silence. Similar is, (Zechariah 2:17) “Be silent, (הס) O all flesh”; (Amos 6:10) “Be silent (הס): for we may not mention [the name of the Lord]”. So is the manner of people: he who wishes to silence a group of men says “sst” (This sibilant sound is therefore used to command silence).

וַיַּ֧הַס כָּלֵ֛ב אֶת־הָעָ֖ם אֶל־מֹשֶׁ֑ה וַיֹּ֗אמֶר עָלֹ֤ה נַעֲלֶה֙ וְיָרַ֣שְׁנוּ אֹתָ֔הּ כִּֽי־יָכ֥וֹל נוּכַ֖ל לָֽהּ׃

And Kalev stilled the people before Moshe, and said, Let us go up at once, and possess it; for we are well able to overcome it.