'Mouth of the Lord' in the Bible

Who is the wise man, that may understand this? and who is he to whom the mouth of the LORD hath spoken, that he may declare it, for what the land perisheth and is burned up like a wilderness, that none passeth through?

Thus saith the LORD of hosts, Hearken not unto the words of the prophets that prophesy unto you: they make you vain: they speak a vision of their own heart, and not out of the mouth of the LORD.