Charles Ellicott Commentary Numbers 24:2

"And Balaam lifted up his eyes, and he saw Israel dwelling according to their tribes; and the Spirit of God came upon him." — Numbers 24:2 (ASV)

Abiding in his tents ... — that is, encamped according to the order prescribed for the respective tribes. The cognate noun is rendered tabernacles in Numbers 24:5.

And the spirit of God came upon him.— In regard to the two former utterances, it is said that Jehovah put a word in the mouth of Balaam (Numbers 23:5; Numbers 23:15). In the present case the Spirit of God came upon (or, over) him. The same expression is used of the messengers of Saul (1 Samuel 19:20), and of Saul himself (in the same book,Numbers 24:23). The prophecy of Caiaphas (John 11:15) affords another instance of the sovereign power of the Spirit as displayed through the medium of wicked men.