"If a prophet or a dreamer of dreams arises among you and gives you a sign or a wonder, and the sign or the wonder comes true, concerning which he spoke to you, saying, 'Let us go after other gods (whom you have not known) and let us serve them,' you shall not listen to the words of that prophet or that dreamer of dreams; for the LORD your God is testing you to find out if you love the LORD your God with all your heart and with all your soul." (Deuteronomy 13:1-3) The literal commandment is that we should not listen to the words of a prophet or dreamer of dreams who tells us to go after other gods and serve them.
"When a prophet speaks in the name of the LORD, if the thing does not come about or come true, that is the thing which the LORD has not spoken. The prophet has spoken it presumptuously; you shall not be afraid of him." (Deuteronomy 18:22) The literal commandment is that we should not be afraid of a false prophet.