Sforno focuses on the mission of the spies and the people's distorted reaction, highlighting that the catastrophe was not simply tactical but spiritual: they refused to rely on divine promise. That makes the meraglim a paradigmatic sin for Moshe’s opening rebuke.
נִשְׁלְחָה אֲנָשִׁים. נִבְחַר אֲנַחְנוּ אֲנָשִׁים וְנִשְׁלַח, וְלָזֶה לֹא הִסְכִּים הָאֵל יִתְעַלֶּה וְאָמַר לְמֹשֶׁה ״שְׁלַח לְךָ״ (במדבר יג:ב) שֶׁיִּבְחַר הוּא הָאֲנָשִׁים וְלֹא הֵם, פֶּן יִבְחֲרוּ הֶדְיוֹטוֹת שֶׁיּוֹסִיפוּ לְהָרַע. וּבְכֵן בָּחַר מֹשֶׁה ״כֻּלָּם אֲנָשִׁים״ (במדבר יג:ג) וּבְתוֹכָם יְהוֹשֻׁעַ וְכָלֵב. וְגַם הָרְשָׁעִים מֵהֶם, אַף עַל פִּי שֶׁהִרְשִׁיעוּ לוֹמַר שֶׁאִי אֶפְשָר לְכָבְשָׁהּ, לֹא הֵעֵזוּ פְנֵיהֶם לוֹמַר שֶׁהָאָרֶץ רָעָה, אֲבָל סִפְּרוּ בְּשִׁבְחָהּ. בְּאֹפֶן שֶׁאַחַר כֵּן שָׁבוּ בִּתְשׁוּבָה, כַּאֲמָרוֹ ״וַתַּעֲנוּ וַתֹּאמְרוּ אֵלַי חָטָאנוּ לַה׳״ (דברים א:מא), ״וַתָּשֻׁבוּ וַתִּבְכּוּ לִפְנֵי ה׳״ (דברים א:מה). וְלֹא אֲבִיתֶם לַעֲלוֹת. שֶׁגִּלִּיתֶם רִשְׁעֲכֶם שֶׁלֹּא הָיָה הַשְּׁלִיחוּת כְּדֵי לִבְחוֹר מִן הָאָרֶץ אֵיזֶה צַד יוֹתֵר טוֹב לָכֶם, כַּאֲשֶׁר חָשַׁבְתִּי וְכַאֲשֶׁר אֲמַרְתֶּם לַעֲשׂוֹת, אֲבָל הָיְתָה כַּוָּנַתְכֶם בַּשְּׁלִיחוּת לִרְאוֹת אִם תּוּכְלוּ לְכָבְשָׁהּ, וְזֶה שֶׁלֹּא הֱיִיתֶם מַאֲמִינִים בַּה׳ שֶׁיִּתְּנֶנָּה לָכֶם. וּלְכֵן כְּשֶׁהִגִּידוּ הַמְרַגְּלִים שֶׁהָעָם חָזָק, לֹא אֲבִיתֶם לַעֲלוֹת.
נשלחה אנשים, “we ourselves want to appoint these men and dispatch them.” This was something G’d did not approve of, and this is why He told Moses: “you dispatch them!” (Numbers 13,2) The men that were to spy out the land were to be appointed by Moses himself, not by a mob. G’d was afraid that the people would appoint totally unsuitable people to be their spies. The Torah had therefore made a point of reporting that the men selected for this task by Moses were all known as outstanding people, כלם אנשים, including such men as Joshua and Calev. Even those among them, who in the end expressed their belief that they could not hope to conquer this land, did not have the effrontery to badmouth the land itself, but praised it as an excellent land. This was also why it was possible for the people to repent their sin, i.e. they had made a faulty judgment in believing the 10 spies’ assessment of the chances of conquering the land. (compare Numbers 13, 41-45. ולא אביתם לעלות, for at that point you revealed your original sinful approach, i.e. that your motivation had not been to select the best part of the country for yourselves at this time, as I had thought, based on what you had said. Your purpose in the mission had been to determine if it was possible to conquer this land, something that revealed that you did not believe G’d’s promise to you. As a result of your lack of belief you accepted what the spies told you when they said that these people are too strong, and you refused to ascend to this land.