Balaam declared that he could only speak what God had spoken, although the prophet kept hoping that God would change His mind,

And God met Balaam, and he said to Him, “I have prepared the seven altars, and I have offered on each altar a bull and a ram” (Numbers 23:4).

Balaam then did as the Lord had spoken, and the prophet meant with the king of Moab, as the king stood by his sacrifices, Moses showed what happened,

Then the Lord put a word in Balaam’s mouth, and said, “Return to Balak, and thus you shall speak.” So he returned to him, and there he was, standing by his burnt offering, he and all the princes of Moab (Numbers 23:5–6).

Balaam appeared to be doing the right thing, but there was always that hope within him that God would decide to curse Israel and then Balaam could receive the vast wealth promised by the king of Moab.
However, the God of heaven is unrelenting, and never changes His word. It says what it says, and we can play around with it all we want, but at the Judgment we will discover that His word has always stood.