Proverbs today reminds us that God has revealed Himself to us exclusively through the Bible:

Pro 30:5  Every word of God is tested; He is a shield to those who take refuge in Him.

Pro 30:6  Do not add to His words Or He will reprove you, and you will be proved a liar.

This is important to note because there are all sorts of false prophets out there that claim to have visions from God, as if they are some sort of spiritual medium that communicates with God on our behalf, and they are basically doing what today’s Proverb warns us against: adding to God’s words.  Over time folks like Jim Jones, David Koresh and even as recently as 2012 false prophets have claimed to know when the rapture was coming and nefariously influenced people into following them.  

This is what the Bible says about listening to people who speak outside of God’s word:

Heb 1:1  God, after He spoke long ago to the fathers in the prophets in many portions and in many ways,

So that right there is the Old Testament where God spoke to us through guys like Isaiah, Amon, Jeremiah etc.

Then our era, or the New Covenant/New Testament, here is what scripture says we should listen to:

Heb 1:2  in these last days has spoken to us in His Son, whom He appointed heir of all things, through whom also He made the world.

That means that Jesus’s life is what we ought to look to for truth, and it is thoroughly revealed to us in all 4 Gospels.  Matthew, Mark, Luke and John are all accounts of Jesus’s life, His teachings and most importantly His atoning work on the cross.  That is what saves us, Jesus…not false teachers.