"And he struck his hands together" (Numbers 24:10) — he beat this one against that one, as it is said, "I will strike My hands together" (Ezekiel 21:22); and this "and he struck" is an expression of striking. He said to him: I said, "I will surely honor you," and your God in whom you trusted has withheld you from honor. He said to him: I already said to your officers whom you sent to me, "I cannot go beyond the mouth of the LORD" (Numbers 22:18). Before he went with the officers of Balak, he would call Him "the LORD my God," but after he went and transgressed the mouth of the LORD, he did not call Him "my God" — for he understood and knew that he had already been banished from the world.
Why Balaam Stopped Calling the LORD His God After Defying Him
Midrash Aggadah, Numbers 24:10
ויספק את כפיו. הכה זו על זו, כמה דתימר אכה כפי (על) [אל] כפי (יחזקאל כא כב), וזה ויספק הוא לשון הכאה. אמר לו אני אמרתי כבד אכבדך, ואלהיך אשר בטחת בו מנעך מכבוד, אמר לו כבר אמרתי לשריך אשר שלחת אלי, לא אוכל לעבור את פי ה', קודם שהלך עם שרי בלק הי' קורא ה' אלהי, ואחר שהלך ועבר את פי ה' לא קראו אלהי, שהבין וידע שכבר נטרד מן העולם: