וַיֹּ֖אמֶר לֹ֣א תַעֲבֹ֑ר וַיֵּצֵ֤א אֱדוֹם֙ לִקְרָאת֔וֹ בְּעַ֥ם כָּבֵ֖ד וּבְיָ֥ד חֲזָקָֽה׃
And he said: ‘Thou shalt not pass through.’ And Edom came out against him with much people, and with a strong hand.
Rashi on Numbers
וביד חזקה AND WITH A STRONG HAND — relying upon our ancestors’ assurance: (Genesis 27:22) “and the hands are the hands of Esau” (cf. Midrash Tanchuma, Beshalach 9 on בשלח)
Siftei Chakhamim
With our grandfather’s assurance. For if not so, why does it say “a strong hand.” Any massive number of people constitutes a strong hand.