וַיַרְא בָּלָּק בֶּן־צִפּוֹר אֵת כׇּל־אֲשֶּר־עָּשָּה יִשְרָּאֵל לָּאֱמֹרִ י׃ וַיָּגׇּר מוֹאָב מִפְּנֵי הָּעָּם מְאֹד כִּי רַב־הוּא וַיָּקׇּץ מוֹאָב מִפְּנֵי בְנֵי יִשְרָּאֵל׃
And Balak... saw all that Yisrael had done to the Emori. And Moav was very afraid of the nation, because they were numerous...
The word אמורי derives from the word אמר, meaning speech. The Tiferes Shlomo explains that this is an allusion to Tefillah - prayer. He reads the verse as saying that Balak saw all that Yisrael had done and accomplished through the power of their prayers.
The Jewish people were not militarily stronger than their opponents, and yet they were miraculously victorious. Balak understood that this is on account of their prayers to Hashem, who then fights on their behalf.
Balak thought that he would do the same; that by praying to Hashem, he would be given victory over the Jewish people. But what Balak failed to understand is that his prayers could not match the quality of the prayers of the Jewish people.
When they Daven, the Jewish people come before Hashem with Teshuvah and the merit of their good deeds. They prepare themselves to approach Hashem with purity, holiness, humility and a pure heart. And their prayers are filled with proper kavana.
To achieve this takes great effort and work. This is the deeper meaning of the next verse. And Moav was afraid of Yisrael because רב הוא, their Avodas Hatefillah takes great effort and preparation. And so מואב ויקץ, they detested Bnei Yisrael, knowing that with the power of the kavana-filled prayers, they would be invincible.
