Isaiah 8:20
To the law and to the testimony: if they speak not according to this word, it is because there is no light in them.
Torrey's Topical Textbook—AKJV

1 John 4:1
Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world.
Torrey's Topical Textbook—AKJV