Bamidbar - Numbers - Chapter 13
- וַיֹּצִ֜יאוּ דִּבַּ֤ת הָאָ֨רֶץ֙ אֲשֶׁ֣ר תָּר֣וּ אֹתָ֔הּ אֶל־בְּנֵ֥י יִשְׂרָאֵ֖ל לֵאמֹ֑ר הָאָ֡רֶץ אֲשֶׁר֩ עָבַ֨רְנוּ בָ֜הּ לָת֣וּר אֹתָ֗הּ אֶ֣רֶץ אֹכֶ֤לֶת יֽוֹשְׁבֶ֨יהָ֙ הִ֔וא וְכָל־הָעָ֛ם אֲשֶׁר־רָאִ֥ינוּ בְתוֹכָ֖הּ אַנְשֵׁ֥י מִדּֽוֹת
"They spread an [evil] report about the land which they had scouted, telling the children of Israel, "The land we passed through to explore is a land that consumes its inhabitants, and all the people we saw in it are men of stature."
Ramban, Bamidbar 13:32-14:1
According to the Ramban, after Caleb spoke in verses 30-31 in verse 32 (shown above) they had already left the presence of Moses and Aaron at this point. This is where they began to say to the people in their tents that the land consumes its inhabitants.
The spies claim that the Land was deadly contradicted what they had said earlier about the fertility of the Land in front of Moses and Aaron that it flows with milk and honey [at Shelach, 13:27]. This was one of the lies they perpetrated to the people in their tents but not while in front of Moses and Aaron. They also embellished their wording to incite despair so the people would not be willing to fight.
Later, in 13:33 they exaggerated their description of the Anak calling them Nephilim descendents of Anak to try to frighten and terrify the people further. (This differs from their description of them in 13:23 where they are referred to merely as יְלִידֵ֖י הָֽעֲנָ֑ק 'descendants of Anak'.)
After some searching I am doubtful whether Anak are truly descendants of Nephilim. It appears the spies lied (with maybe some possibility in their minds that it could be true to justify portraying such a lie). I have not come across any hard evidence. How would the spies truly know the sons of Anak were from Nephilim besides some 'weak unverified evidence' of their historical account which the Ramban addresses in his commentary at 13:33. This seems to be the way (at least I interpret) the Ramban is portraying this idea of the spies having lied.
הם "מן הנפלים" הקדמונים אשר שמעתם עליהם כי המה הגבורים "אשר מעולם אנשי השם" (בראשית ו ד). They are from "the Nephilim" of the ancient times whom you have heard about them for they were the mighty, "who are from old, men of reknown".
ולפי שהיה ענין הנפילים שבדורות נח נודע בעולם, הזכירו להם שאלו בני הענק מהם, כדי ליראם ולבהלם. ולכך אמרו עתה "ונהי בעינינו כחגבים וכן היינו בעיניהם "And since they were the Niphilim that were in the generations of Noah were known throughout the world they mentioned to them that they were, the sons of Anak from them"
Also in Genesis Rabbah 26:7 Nephilim are referred to as seven names and Anakim is indeed one of them.
הַנְּפִלִים הָיוּ בָאָרֶץ בַּיָּמִים הָהֵם (בראשית ו, ד), שִׁבְעָה שֵׁמוֹת נִקְרְאוּ לָהֶם, אֵימִים,
רְפָאִים, גִּבּוֹרִים, זַמְזֻמִּים, עֲנָקִים, עַוִּים, נְפִלִים
However there is a footnote by Yefeh To'ar in the Artscroll Midrash Rabbah that clarifies they were not proginators of the giants in Deuteronomy, for the giants referred to in Genesis 6:4 were destroyed in the Flood. The seven names are meant to reference families of giants before and after the Flood.