The saying shows that the false teachers formerly followed true doctrine and the rules of a good life. Later, however, they fell away from the truth and gave themselves over to intellectual and moral corruption and impiety. They went astray and took a wrong path, namely, the path of Balaam. This was the path that Balaam marked out, or on which he himself walked, the path of covetousness.
The history of Balaam is told from Numbers chapter 22 onward. The son of Bosor, according to the ancient pronunciation and reading, means the son of Beor.
He loved the wages of unrighteousness. These unrighteous wages were the gifts brought, or presented, to Balaam by the messengers sent to him in the name of King Balak (Num 22:7). These wages are called unrighteous because Balaam hoped through them to do an unrighteous and godless deed, namely, to pronounce a curse upon Israel.
He loved is a somewhat softened expression, yet it fully corresponds to the circumstances of the narrative. The account does not expressly mention Balaam's covetousness. It presents him as acting according to the will of God.
Yet the narrative also shows that, when the second embassy brought still richer gifts, he urged the messengers to remain with him longer. He wished to inquire of God again about what he should do. In this way he seemed to force, or extort, permission from God to go with Balak's envoys. Therefore the wrath of God was kindled against Balaam because he went with them (Num 22:22).
From the connection of the narrative, Balaam himself soon understood that there was a sinful passion in his heart at this point (Num 22:34). The apostle's eye discerned this passion in the fact that he loved the wages of unrighteousness.