Targum zu Bamidbar 25:1

And Israel dwelt in the place which is called Shittim, on account of the (Shetutha) foolishness and depravity which were among them. And the people began to profane their holiness, and to strip their bodies to the image of Peor, and commit fornication with the daughters of the Moabites, who brought out the image of Peor, concealed under their bundles.

And Israel abode in Shittim; and the people began to commit fornication with the daughters of the Moabites.