Not Even the Apostles Had Their Own Doctrine

We, however, are not permitted to cherish any doctrine coming from our own will, nor to choose those doctrines which another has introduced from his private fancy. In the Lord’s apostles we possess our authority; for even they did not choose to introduce anything of themselves, but instead faithfully delivered to the nations the doctrine which they had received from Christ. If, therefore, even “an angel from heaven should preach any other gospel” than the one delivered by the apostles, he would be called accursed by us.
-- Tertullian, from his work Prescription Against Heretics