What does challah have to do with the scouts? Parashat Shlach Lcha
(א) וַיְדַבֵּ֥ר יְהֹוָ֖ה אֶל־מֹשֶׁ֥ה לֵּאמֹֽר׃ (ב) שְׁלַח־לְךָ֣ אֲנָשִׁ֗ים וְיָתֻ֙רוּ֙ אֶת־אֶ֣רֶץ כְּנַ֔עַן אֲשֶׁר־אֲנִ֥י נֹתֵ֖ן לִבְנֵ֣י יִשְׂרָאֵ֑ל אִ֣ישׁ אֶחָד֩ אִ֨ישׁ אֶחָ֜ד לְמַטֵּ֤ה אֲבֹתָיו֙ תִּשְׁלָ֔חוּ כֹּ֖ל נָשִׂ֥יא בָהֶֽם׃ (ג) וַיִּשְׁלַ֨ח אֹתָ֥ם מֹשֶׁ֛ה מִמִּדְבַּ֥ר פָּארָ֖ן עַל־פִּ֣י יְהֹוָ֑ה כֻּלָּ֣ם אֲנָשִׁ֔ים רָאשֵׁ֥י בְנֵֽי־יִשְׂרָאֵ֖ל הֵֽמָּה׃
(1) יהוה spoke to Moses, saying, (2) “Send agents to scout the land of Canaan, which I am giving to the Israelite people; send one participant from each of their ancestral tribes, each one a chieftain among them.” (3) So Moses, by יהוה’s command, sent them out from the wilderness of Paran, all of them being men of consequence, leaders of the Israelites.
(יז) וַיְדַבֵּ֥ר יְהֹוָ֖ה אֶל־מֹשֶׁ֥ה לֵּאמֹֽר׃ (יח) דַּבֵּר֙ אֶל־בְּנֵ֣י יִשְׂרָאֵ֔ל וְאָמַרְתָּ֖ אֲלֵהֶ֑ם בְּבֹֽאֲכֶם֙ אֶל־הָאָ֔רֶץ אֲשֶׁ֥ר אֲנִ֛י מֵבִ֥יא אֶתְכֶ֖ם שָֽׁמָּה׃ (יט) וְהָיָ֕ה בַּאֲכׇלְכֶ֖ם מִלֶּ֣חֶם הָאָ֑רֶץ תָּרִ֥ימוּ תְרוּמָ֖ה לַיהֹוָֽה׃ (כ) רֵאשִׁית֙ עֲרִסֹ֣תֵכֶ֔ם חַלָּ֖ה תָּרִ֣ימוּ תְרוּמָ֑ה כִּתְרוּמַ֣ת גֹּ֔רֶן כֵּ֖ן תָּרִ֥ימוּ אֹתָֽהּ׃ (כא) מֵרֵאשִׁית֙ עֲרִסֹ֣תֵיכֶ֔ם תִּתְּנ֥וּ לַיהֹוָ֖ה תְּרוּמָ֑ה לְדֹרֹ֖תֵיכֶֽם׃ {ס}
(17) יהוה spoke to Moses, saying: (18) Speak to the Israelite people and say to them: When you enter the land to which I am taking you (19) and you eat of the bread of the land, you shall set some aside as a gift to יהוה: (20) as the first yield of your baking, you shall set aside a loaf as a gift; you shall set it aside as a gift like the gift from the threshing floor. (21) You shall make a gift to יהוה from the first yield of your baking, throughout the ages.

ראשית עריסותיכם חלה תרימו תרומה. מצות חלה אינה נוהגת במדבר, אבל נתחייבו בה מיד בכניסתן לארץ. ומה שהזכיר לשון מלחם הארץ הוצרך לומר כן לפי שבמדבר היו אוכלים לחם השמים שהיה קדוש, ולכך צוה כי כשיבאו לארץ ויאכלו מלחם הארץ שיקדשו אותה במצוה והיא מצות חלה

(14th c Spain)

The mitzvah of challah-taking was not applicable in the wilderness, but this commandment became applicable as soon as they entered the land. The reason the Torah had to use the words “from the bread of the land,” is that in the wilderness they ate the bread of heaven which was holy, and therefore God commanded [challah-taking] so that when they will come to the land and will eat bread of the land, it will be sanctified through the mitzvah of challah-taking.

חלה תרימו תרומה אחר חטא המרגלים הצריך גם החלה למען יהיו ראויים שתחול ברכה בבתיהם כאמרו וראשית עריסותיכם תתנו לכהן להניח ברכה אל ביתך וכן אליהו עשי לי משם עגה קטנה בראשונה והוצאת לי (ולך ולבנך תעשי באחרונה) כי כה אמר ה' כד הקמח לא תכלה:

(16th c Italy)

After the sin of the spies, challah-taking became a necessity for their individual homes to enjoy God’s blessing. As it is said (Ezekiel 44:30):“You shall give the first of the yield of your baking to the priest, that a blessing may rest upon your home.” This practice had already been displayed when Elijah, assisting the impoverished widow, commanded her to first give to him a small cake of the little flour she had left, as God had said that in such a case the jar of flour in her house would not become empty during the remainder of the famine. (Kings I 17,13-14)

R. Joseph Soloveitchik (20th c USA)
Rabbi Soloveitchik asked why the mitzvah of challah-taking is taught in this parashah? Why is it not mentioned in next week’s parashah together with the other produce-related, Eretz Yisrael-dependent laws, such as Terumah? [See Numbers 18:12-18]
The commandment to separate Challah is different from Mitzvot such as Terumah [heave offering] and Ma’aser [tithe offering] in that the latter apply to the produce of Eretz Yisrael wherever the produce may be, while the former applies to a dough kneaded in Eretz Yisrael regardless of where the wheat grew. Terumah and Ma’aser are indicative of the intrinsic holiness of Eretz Yisrael and of the blessing attributable to the Land itself. Not so Challah. That mitzvah is a reminder of God’s blessing that rests on the handiwork of the residents of Eretz Yisrael.
The mitzvah of Challah belongs specifically after the episode of the Spies, for their very doubt was whether the Israelites were strong enough to conquer and inhabit the Land. In the context of those doubts, the Torah teaches that the efforts of those who inhabit the Land are blessed.

(ט) אַ֣ךְ בַּיהֹוָה֮ אַל־תִּמְרֹ֒דוּ֒ וְאַתֶּ֗ם אַל־תִּֽירְאוּ֙ אֶת־עַ֣ם הָאָ֔רֶץ כִּ֥י לַחְמֵ֖נוּ הֵ֑ם סָ֣ר צִלָּ֧ם מֵעֲלֵיהֶ֛ם וַֽיהֹוָ֥ה אִתָּ֖נוּ אַל־תִּירָאֻֽם׃

(9) only you must not rebel against the LORD. Have no fear then of the people of the country, for they are our prey [lechem]: their protection has departed from them, but the LORD is with us. Have no fear of them!”

כי לחמנו הם. נֹאכְלֵם כַּלֶּחֶם:
כי לחמנו הם FOR THEY ARE BREAD FOR US — i.e. we shall consume them as bread.