'Congregation of the Lord' in the Bible

Thus says the whole congregation of the LORD, What trespass is this that you have committed against the God of Israel, to turn away this day from following the LORD, in that you have built you an altar, that you might rebel this day against the LORD?

Is the iniquity of Peor too little for us, from which we are not cleansed until this day, although there was a plague in the congregation of the LORD,