Adam Clarke on Psalms 106:28

They joined themselves also unto Baalpeor - The Vulgate, Septuagint, and others, have Belphegor; the Syriac and Arabic, the idol Phegor, or Phaaur; the ע ain in the word being pronounced as gh.

Ate the sacrifices or the dead - מתים methim, of dead men. Most of the heathen idols were seen, who had been deified after their death; many of whom had been execrated during their life.