We are from God. Whoever knows God listens to us; whoever is not from God does not listen to us. That is how we know the Spirit of truth and the spirit of deception.
KJV
We are of God: he that knoweth God heareth us; he that is not of God heareth not us. Hereby know we the spirit of truth, and the spirit of error.
ASV
We are of God: he that knoweth God heareth us; he who is not of God heareth us not. By this we know the spirit of truth, and the spirit of error.