民数記 22:2

וירא בלק ... את כל אשר עשה ישראל לאמרי AND BALAK … SAW ALL THAT ISRAEL HAD DONE TO THE AMORITES — He said to his people: Those two kings (Sihon and Og) on whom we relied (see Rashi on Numbers 21:23) could not resist them; how much less can we do so; on this account (because he said this to his people) ויגר מואב MOAB (the whole people) WAS SORE AFRAID (Midrash Tanchuma, Balak 2).

And Balaq the son of Żippor saw all that Yisra᾽el had done to the Emori.

וַיַּ֥רְא בָּלָ֖ק בֶּן־צִפּ֑וֹר אֵ֛ת כׇּל־אֲשֶׁר־עָשָׂ֥ה יִשְׂרָאֵ֖ל לָֽאֱמֹרִֽי׃