Adam Clarke on Psalms 106:39

And went a whoring - By fornication, whoredom, and idolatry, the Scripture often expresses idolatry and idolatrous acts. I have given the reason of this in other places. Besides being false to the true God, to whom they are represented as betrothed and married, (and their acts of idolatry were breaches of this solemn engagement), the worship of idols was frequently accompanied with various acts of impurity.

The translation in the Anglo-Saxon is very remarkable: and they fornicated. In Anglo-Saxon, signifies to fire, to ignite; to commit adultery. So is a prostitute, a whore; and is to go a whoring, to fornicate; probably from, or to fire, and to lie, or a glutton, - one who lies with fire, who is ignited by it, who is greedily intent upon the act by which he is inflamed. And do not the words themselves show that in former times whoredom was punished, as it is now, by a disease which produces the sensation of burning in the unhappy prostitutes, whether male or female? And to this meaning the following seems particularly to be applicable.