The Smart Donkey Series: Prologue

Then the Israelites traveled to the plains of Moab and camped along the Jordan across from Jericho. Now Balak son of Zippor saw all that Israel had done to the Amorites, and Moab was terrified because there were so many people. Indeed, Moab was filled with dread because of the Israelites. The Moabites said to the elders of Midian, "This horde is going to lick up everything around us, as an ox licks up the grass of the field." 
So Balak son of Zippor, who was king of Moab at that time, sent messengers to summon Balaam son of Beor, who was at Pethor, near the River, in his native land. Balak said: "A people has come out of Egypt; they cover the face of the land and have settled next to me. Now come and put a curse on these people, because they are too powerful for me. Perhaps then I will be able to defeat them and drive them out of the country. For I know that those you bless are blessed, and those you curse are cursed." The elders of Moab and Midian left, taking with them the fee for divination.
When they came to Balaam, they told him what Balak had said. "Spend the night here," Balaam said to them, "and I will bring you back the answer the LORD gives me." So the Moabite princes stayed with him.

This part just makes me wonder what Balaam was thinking...I don't know why he would even ask God if he should curse his chosen people.

God came to Balaam and asked, "Who are these men with you?" 
Balaam said to God, "Balak son of Zippor, king of Moab, sent me this message:A people that has come out of Egypt covers the face of the land. Now come and put a curse on them for me. Perhaps then I will be able to fight them and drive them away.'"
But God said to Balaam, "Do not go with them. You must not put a curse on those people, because they are blessed."
The next morning Balaam got up and said to Balak's princes, "Go back to your own country, for the LORD has refused to let me go with you."
So the Moabite princes returned to Balak and said, "Balaam refused to come with us."
Then Balak sent other princes, more numerous and more distinguished than the first. They came to Balaam and said: "This is what Balak son of Zippor says: Do not let anything keep you from coming to me, because I will reward you handsomely and do whatever you say. Come and put a curse on these people for me."

Now Balaam is being bribed...don't listen to them!

But Balaam answered them, "Even if Balak gave me his palace filled with silver and gold, I could not do anything great or small to go beyond the command of the LORD my God.
Now stay here tonight as the others did, and I will find out what else the LORD will tell me."

I wonder if Balaam really meant that. The reward might have tempted him.

That night God came to Balaam and said, "Since these men have come to summon you, go with them, but do only what I tell you."
Balaam got up in the morning, saddled his donkey and went with the princes of Moab. But God was very angry when he went, and the angel of the LORD stood in the road to oppose him. Balaam was riding on his donkey, and his two servants were with him.
Number 22:1-22

To be continued...
I can see God sighing, and wondering why Balaam fell into temptation

Woe to them! They have taken the way of Cain; they have rushed for profit into Balaam's error; they have been destroyed in Korah's rebellion.
Jude 1:11

Jude says that Balaam was in it for the money. 

They have left the straight way and wandered off to follow the way of Balaam son of Beor, who loved the wages of wickedness.
2 Peter 2:15

And says the same, that wickness won Balaam over. And God was very angry with him...