So long as Moses lived this angel was held in check by him, and if he tried, even when Israel sinned, to rise out of the depths, open wide his mouth, and destroy Israel with his panting, all Moses had to do was to utter the name of God, and Haron, or as he is sometimes called, Peor, was drawn once more into the depths of the earth. At Moses' death, God buried him opposite the spot where Peor is bound. For should Peor, if Israel sinned, reach the upper world and open his mouth to destroy Israel with his panting, he would, upon seeing Moses' grave, be so terror-stricken, that he would fall back into the depths once more.
Death of Haron
Legends of the Jews 2:104