Rashi on Numbers 22:10/רש"י על במדבר כ״ב:י׳

1בלק בן צפור וגו׳ BALAK THE SON OF ZIPPOR [KING OF MOAB, HAS SENT TO ME] — Although I am of no importance in Your eyes, I am of importance in the eyes of kings (Midrash Tanchuma, Balak 5).